Schema - Agent Client Protocol

The schema file can be downloaded directly from the latest GitHub release.

Agent

Defines the interface that all ACP-compliant agents must implement. Agents are programs that use generative AI to autonomously modify code. They handle requests from clients and execute tasks using language models and tools.

authenticate

Authenticates the client using the specified authentication method. Called when the agent requires authentication before allowing session creation. The client provides an authentication method ID that was advertised during initialization and whose type defines the authenticate flow. After successful authentication, the client can proceed to create sessions with new_session without receiving an auth_required error. See protocol docs: Initialization

AuthenticateRequest

Request parameters for the authenticate method. Specifies which authentication method to use. Type: Object Properties:

object | null

The _meta property is reserved by ACP to allow clients and agents to attach additional metadata to their interactions. Implementations MUST NOT make assumptions about values at these keys.See protocol docs: Extensibility

AuthMethodId

required

The ID of the authentication method to use. Must be one of the methods advertised in the initialize response.

AuthenticateResponse

Response to the authenticate method. Type: Object Properties:

object | null

document/didChange

UNSTABLE Notification sent when a file is edited.

DidChangeDocumentNotification

Notification sent when a file is edited. Type: Object Properties:

object | null

TextDocumentContentChangeEvent[]

required

The content changes.

SessionId

required

The session ID for this notification.

string

required

The URI of the changed document.

int64

required

The new version number of the document.

document/didClose

UNSTABLE Notification sent when a file is closed.

DidCloseDocumentNotification

Notification sent when a file is closed. Type: Object Properties:

object | null

SessionId

required

The session ID for this notification.

string

required

The URI of the closed document.

document/didFocus

UNSTABLE Notification sent when a file becomes the active editor tab.

DidFocusDocumentNotification

Notification sent when a file becomes the active editor tab. Type: Object Properties:

object | null

Position

required

The current cursor position.

SessionId

required

The session ID for this notification.

string

required

The URI of the focused document.

int64

required

The version number of the document.

Range

required

The portion of the file currently visible in the editor viewport.

document/didOpen

UNSTABLE Notification sent when a file is opened in the editor.

DidOpenDocumentNotification

Notification sent when a file is opened in the editor. Type: Object Properties:

object | null

string

required

The language identifier of the document (e.g., “rust”, “python”).

SessionId

required

The session ID for this notification.

string

required

The full text content of the document.

string

required

The URI of the opened document.

int64

required

The version number of the document.

document/didSave

UNSTABLE Notification sent when a file is saved.

DidSaveDocumentNotification

Notification sent when a file is saved. Type: Object Properties:

object | null

SessionId

required

The session ID for this notification.

string

required

The URI of the saved document.

initialize

Establishes the connection with a client and negotiates protocol capabilities. This method is called once at the beginning of the connection to:

Negotiate the protocol version to use
Exchange capability information between client and agent
Determine available authentication methods

The agent should respond with its supported protocol version and capabilities. See protocol docs: Initialization

InitializeRequest

Request parameters for the initialize method. Sent by the client to establish connection and negotiate capabilities. See protocol docs: Initialization Type: Object Properties:

object | null

ClientCapabilities

Capabilities supported by the client.

Default: {"fs":{"readTextFile":false,"writeTextFile":false},"terminal":false,"auth":{"terminal":false}}

Implementation | null

Information about the Client name and version sent to the Agent.Note: in future versions of the protocol, this will be required.

ProtocolVersion

required

The latest protocol version supported by the client.

InitializeResponse

Response to the initialize method. Contains the negotiated protocol version and agent capabilities. See protocol docs: Initialization Type: Object Properties:

object | null

AgentCapabilities

Capabilities supported by the agent.

Default: {"loadSession":false,"promptCapabilities":{"image":false,"audio":false,"embeddedContext":false},"mcpCapabilities":{"http":false,"sse":false,"acp":false},"sessionCapabilities":{},"auth":{}}

Implementation | null

Information about the Agent name and version sent to the Client.Note: in future versions of the protocol, this will be required.

AuthMethod[]

Authentication methods supported by the agent.

Default: []

ProtocolVersion

required

The protocol version the client specified if supported by the agent, or the latest protocol version supported by the agent.The client should disconnect, if it doesn’t support this version.

logout

Logs out of the current authenticated state. After a successful logout, all new sessions will require authentication. There is no guarantee about the behavior of already running sessions.

LogoutRequest

Request parameters for the logout method. Terminates the current authenticated session. Type: Object Properties:

object | null

LogoutResponse

Response to the logout method. Type: Object Properties:

object | null

mcp/message

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Exchanges an MCP-over-ACP message.

MessageMcpNotification

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Notification parameters for mcp/message. This is used when the wrapped MCP message is a notification and the outer JSON-RPC envelope has no id. Type: Object Properties:

object | null

McpConnectionId

required

The MCP-over-ACP connection this message is sent on.

string

required

The inner MCP method name.

object | null

Optional inner MCP params.If omitted or set to null, the inner MCP message has no params.

MessageMcpRequest

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Request parameters for mcp/message. Type: Object Properties:

object | null

McpConnectionId

required

The MCP-over-ACP connection this message is sent on.

string

required

The inner MCP method name.

object | null

Optional inner MCP params.If omitted or set to null, the inner MCP message has no params.

MessageMcpResponse

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Response to mcp/message. This is the inner MCP response result payload. Any JSON value is valid.

nes/accept

UNSTABLE Notification sent when a suggestion is accepted.

AcceptNesNotification

Notification sent when a suggestion is accepted. Type: Object Properties:

object | null

NesSuggestionId

required

The ID of the accepted suggestion.

SessionId

required

The session ID for this notification.

nes/close

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Closes an active NES session and frees up any resources associated with it. The agent must cancel any ongoing work and then free up any resources associated with the NES session.

CloseNesRequest

Request to close an NES session. The agent must cancel any ongoing work related to the NES session and then free up any resources associated with the session. Type: Object Properties:

object | null

SessionId

required

The ID of the NES session to close.

CloseNesResponse

Response from closing an NES session. Type: Object Properties:

object | null

nes/reject

UNSTABLE Notification sent when a suggestion is rejected.

RejectNesNotification

Notification sent when a suggestion is rejected. Type: Object Properties:

object | null

NesSuggestionId

required

The ID of the rejected suggestion.

NesRejectReason | null

The reason for rejection.

SessionId

required

The session ID for this notification.

nes/start

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Starts an NES session.

StartNesRequest

Request to start an NES session. Type: Object Properties:

object | null

NesRepository | null

Repository metadata, if the workspace is a git repository.

WorkspaceFolder[] | null

The workspace folders.

string | null

The root URI of the workspace.

StartNesResponse

Response to nes/start. Type: Object Properties:

object | null

SessionId

required

The session ID for the newly started NES session.

nes/suggest

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Requests a code suggestion.

SuggestNesRequest

Request for a code suggestion. Type: Object Properties:

object | null

NesSuggestContext | null

Context for the suggestion, included based on agent capabilities.

Position

required

The current cursor position.

Range | null

The current text selection range, if any.

SessionId

required

The session ID for this request.

NesTriggerKind

required

What triggered this suggestion request.

string

required

The URI of the document to suggest for.

int64

required

The version number of the document.

SuggestNesResponse

Response to nes/suggest. Type: Object Properties:

object | null

NesSuggestion[]

required

The list of suggestions.

providers/disable

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Disables a provider.

DisableProviderRequest

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Request parameters for providers/disable. Type: Object Properties:

object | null

ProviderId

required

Provider ID to disable.

DisableProviderResponse

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Response to providers/disable. Type: Object Properties:

object | null

providers/list

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Lists providers that can be configured by the client.

ListProvidersRequest

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Request parameters for providers/list. Type: Object Properties:

object | null

ListProvidersResponse

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Response to providers/list. Type: Object Properties:

object | null

ProviderInfo[]

required

Configurable providers with current routing info suitable for UI display.

providers/set

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Replaces the configuration for a provider.

SetProviderRequest

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Request parameters for providers/set. Replaces the full configuration for one provider ID. Type: Object Properties:

object | null

LlmProtocol

required

Protocol type for this provider.

string

required

Base URL for requests sent through this provider.

object

Full headers map for this provider. May include authorization, routing, or other integration-specific headers.

ProviderId

required

Provider ID to configure.

SetProviderResponse

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Response to providers/set. Type: Object Properties:

object | null

session/cancel

Cancels ongoing operations for a session. This is a notification sent by the client to cancel an ongoing prompt turn. Upon receiving this notification, the Agent SHOULD:

Stop all language model requests as soon as possible
Abort all tool call invocations in progress
Send any pending session/update notifications
Respond to the original session/prompt request with StopReason::Cancelled

See protocol docs: Cancellation

CancelNotification

Notification to cancel ongoing operations for a session. See protocol docs: Cancellation Type: Object Properties:

object | null

SessionId

required

The ID of the session to cancel operations for.

session/close

Closes an active session and frees up any resources associated with it. This method is only available if the agent advertises the sessionCapabilities.close capability. The agent must cancel any ongoing work (as if session/cancel was called) and then free up any resources associated with the session.

CloseSessionRequest

Request parameters for closing an active session. If supported, the agent must cancel any ongoing work related to the session (treat it as if session/cancel was called) and then free up any resources associated with the session. Only available if the Agent supports the sessionCapabilities.close capability. Type: Object Properties:

object | null

SessionId

required

The ID of the session to close.

CloseSessionResponse

Response from closing a session. Type: Object Properties:

object | null

session/delete

Deletes an existing session from session/list. This method is only available if the agent advertises the sessionCapabilities.delete capability.

DeleteSessionRequest

Request parameters for deleting an existing session from session/list. Only available if the Agent supports the sessionCapabilities.delete capability. Type: Object Properties:

object | null

SessionId

required

The ID of the session to delete.

DeleteSessionResponse

Response from deleting a session. Type: Object Properties:

object | null

session/fork

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Forks an existing session to create a new independent session. This method is only available if the agent advertises the session.fork capability. The agent should create a new session with the same conversation context as the original, allowing operations like generating summaries without affecting the original session’s history.

ForkSessionRequest

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Request parameters for forking an existing session. Creates a new session based on the context of an existing one, allowing operations like generating summaries without affecting the original session’s history. Only available if the Agent supports the session.fork capability. Type: Object Properties:

object | null

"string"[]

string

required

The working directory for this session. Must be an absolute path.

McpServer[]

List of MCP servers to connect to for this session.

SessionId

required

The ID of the session to fork.

ForkSessionResponse

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Response from forking an existing session. Type: Object Properties:

object | null

SessionConfigOption[] | null

Initial session configuration options if supported by the Agent.

SessionModeState | null

Initial mode state if supported by the AgentSee protocol docs: Session Modes

SessionId

required

Unique identifier for the newly created forked session.

session/list

Lists existing sessions known to the agent. This method is only available if the agent advertises the sessionCapabilities.list capability. The agent should return metadata about sessions with optional filtering and pagination support.

ListSessionsRequest

Request parameters for listing existing sessions. Only available if the Agent supports the sessionCapabilities.list capability. Type: Object Properties:

object | null

string | null

Opaque cursor token from a previous response’s nextCursor field for cursor-based pagination

string | null

Filter sessions by working directory. Must be an absolute path.

ListSessionsResponse

Response from listing sessions. Type: Object Properties:

object | null

string | null

Opaque cursor token. If present, pass this in the next request’s cursor parameter to fetch the next page. If absent, there are no more results.

SessionInfo[]

required

Array of session information objects

session/load

Loads an existing session to resume a previous conversation. This method is only available if the agent advertises the loadSession capability. The agent should:

Restore the session context and conversation history
Connect to the specified MCP servers
Stream the entire conversation history back to the client via notifications

See protocol docs: Loading Sessions

LoadSessionRequest

Request parameters for loading an existing session. Only available if the Agent supports the loadSession capability. See protocol docs: Loading Sessions Type: Object Properties:

object | null

"string"[]

Additional workspace roots to activate for this session. Each path must be absolute.When omitted or empty, no additional roots are activated. When non-empty, this is the complete resulting additional-root list for the loaded session. It may differ from any previously used or reported list as long as the request cwd matches the session’s cwd.

string

required

The working directory for this session. Must be an absolute path.

McpServer[]

required

List of MCP servers to connect to for this session.

SessionId

required

The ID of the session to load.

LoadSessionResponse

Response from loading an existing session. Type: Object Properties:

object | null

SessionConfigOption[] | null

Initial session configuration options if supported by the Agent.

SessionModeState | null

Initial mode state if supported by the AgentSee protocol docs: Session Modes

session/new

Creates a new conversation session with the agent. Sessions represent independent conversation contexts with their own history and state. The agent should:

Create a new session context
Connect to any specified MCP servers
Return a unique session ID for future requests

May return an auth_required error if the agent requires authentication. See protocol docs: Session Setup

NewSessionRequest

Request parameters for creating a new session. See protocol docs: Creating a Session Type: Object Properties:

object | null

"string"[]

Additional workspace roots for this session. Each path must be absolute.These expand the session’s filesystem scope without changing cwd, which remains the base for relative paths. When omitted or empty, no additional roots are activated for the new session.

string

required

The working directory for this session. Must be an absolute path.

McpServer[]

required

List of MCP (Model Context Protocol) servers the agent should connect to.

NewSessionResponse

Response from creating a new session. See protocol docs: Creating a Session Type: Object Properties:

object | null

SessionConfigOption[] | null

Initial session configuration options if supported by the Agent.

SessionModeState | null

Initial mode state if supported by the AgentSee protocol docs: Session Modes

SessionId

required

Unique identifier for the created session.Used in all subsequent requests for this conversation.

session/prompt

Processes a user prompt within a session. This method handles the whole lifecycle of a prompt:

Receives user messages with optional context (files, images, etc.)
Processes the prompt using language models
Reports language model content and tool calls to the Clients
Requests permission to run tools
Executes any requested tool calls
Returns when the turn is complete with a stop reason

See protocol docs: Prompt Turn

PromptRequest

Request parameters for sending a user prompt to the agent. Contains the user’s message and any additional context. See protocol docs: User Message Type: Object Properties:

object | null

ContentBlock[]

required

The blocks of content that compose the user’s message.As a baseline, the Agent MUST support ContentBlock::Text and ContentBlock::ResourceLink, while other variants are optionally enabled via PromptCapabilities.The Client MUST adapt its interface according to PromptCapabilities.The client MAY include referenced pieces of context as either ContentBlock::Resource or ContentBlock::ResourceLink.When available, ContentBlock::Resource is preferred as it avoids extra round-trips and allows the message to include pieces of context from sources the agent may not have access to.

SessionId

required

The ID of the session to send this user message to

PromptResponse

Response from processing a user prompt. See protocol docs: Check for Completion Type: Object Properties:

object | null

StopReason

required

Indicates why the agent stopped processing the turn.

Usage | null

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.Token usage for this turn (optional).

session/resume

Resumes an existing session without returning previous messages. This method is only available if the agent advertises the sessionCapabilities.resume capability. The agent should resume the session context, allowing the conversation to continue without replaying the message history (unlike session/load).

ResumeSessionRequest

Request parameters for resuming an existing session. Resumes an existing session without returning previous messages (unlike session/load). This is useful for agents that can resume sessions but don’t implement full session loading. Only available if the Agent supports the sessionCapabilities.resume capability. Type: Object Properties:

object | null

"string"[]

Additional workspace roots to activate for this session. Each path must be absolute.When omitted or empty, no additional roots are activated. When non-empty, this is the complete resulting additional-root list for the resumed session. It may differ from any previously used or reported list as long as the request cwd matches the session’s cwd.

string

required

The working directory for this session. Must be an absolute path.

McpServer[]

List of MCP servers to connect to for this session.

SessionId

required

The ID of the session to resume.

ResumeSessionResponse

Response from resuming an existing session. Type: Object Properties:

object | null

SessionConfigOption[] | null

Initial session configuration options if supported by the Agent.

SessionModeState | null

Initial mode state if supported by the AgentSee protocol docs: Session Modes

session/set_config_option

Sets the current value for a session configuration option.

SetSessionConfigOptionRequest

Request parameters for setting a session configuration option. Type: Union Shared properties:

object | null

SessionConfigId

required

The ID of the configuration option to set.

SessionId

required

The ID of the session to set the configuration option for.

Variants:

object

A boolean value (type: "boolean").

Show Properties

string

required

The discriminator value. Must be "boolean".

boolean

required

The boolean value.

object

A SessionConfigValueId string value.This is the default when type is absent on the wire. Unknown type values with string payloads also gracefully deserialize into this variant.

Show Properties

SessionConfigValueId

required

The value ID.

SetSessionConfigOptionResponse

Response to session/set_config_option method. Type: Object Properties:

object | null

SessionConfigOption[]

required

The full set of configuration options and their current values.

session/set_mode

Sets the current mode for a session. Allows switching between different agent modes (e.g., “ask”, “architect”, “code”) that affect system prompts, tool availability, and permission behaviors. The mode must be one of the modes advertised in availableModes during session creation or loading. Agents may also change modes autonomously and notify the client via current_mode_update notifications. This method can be called at any time during a session, whether the Agent is idle or actively generating a response. See protocol docs: Session Modes

SetSessionModeRequest

Request parameters for setting a session mode. Type: Object Properties:

object | null

SessionModeId

required

The ID of the mode to set.

SessionId

required

The ID of the session to set the mode for.

SetSessionModeResponse

Response to session/set_mode method. Type: Object Properties:

object | null

Client

Defines the interface that ACP-compliant clients must implement. Clients are typically code editors (IDEs, text editors) that provide the interface between users and AI agents. They manage the environment, handle user interactions, and control access to resources.

elicitation/complete

Notification that a URL-based elicitation has completed. See protocol docs: Elicitation

CompleteElicitationNotification

Notification sent by the agent when a URL-based elicitation is complete. Type: Object Properties:

object | null

ElicitationId

required

The ID of the elicitation that completed.

elicitation/create

Requests structured user input via a form or URL. See protocol docs: Elicitation

CreateElicitationRequest

Request from the agent to elicit structured user input. The agent sends this to the client to request information from the user, either via a form or by directing them to a URL. Elicitations are tied to a session (optionally a tool call) or a request. Type: Union Shared properties:

object | null

string

required

A human-readable message describing what input is needed.

Variants:

object

Form-based elicitation where the client renders a form from the provided schema.

Show Properties

string

required

The discriminator value. Must be "form".

ElicitationSchema

required

A JSON Schema describing the form fields to present to the user.

object

URL-based elicitation where the client directs the user to a URL.

Show Properties

ElicitationId

required

The unique identifier for this elicitation.

string

required

The discriminator value. Must be "url".

string

required

The URL to direct the user to.

Format: uri

object

Custom or future elicitation mode.Values beginning with _ are reserved for implementation-specific extensions. Unknown values that do not begin with _ are reserved for future ACP variants.Clients that do not understand this mode should preserve the raw payload when storing, replaying, proxying, or forwarding elicitation requests. They MUST NOT render it as a known elicitation mode.

Show Properties

string

required

Custom or future elicitation mode.Values beginning with _ are reserved for implementation-specific extensions. Unknown values that do not begin with _ are reserved for future ACP variants.

CreateElicitationResponse

Response from the client to an elicitation request. Type: Union Shared properties:

object | null

Variants:

object

The user accepted and provided content.

Show Properties

string

required

The discriminator value. Must be "accept".

object | null

The user-provided content, if any, as an object matching the requested schema.

object

The user declined the elicitation.

Show Properties

string

required

The discriminator value. Must be "decline".

object

The elicitation was cancelled.

Show Properties

string

required

The discriminator value. Must be "cancel".

object

Custom or future elicitation action.Values beginning with _ are reserved for implementation-specific extensions. Unknown values that do not begin with _ are reserved for future ACP variants.Agents that do not understand this action should preserve the raw payload when storing, replaying, proxying, or forwarding elicitation responses. They MUST NOT treat it as a known elicitation action.

Show Properties

string

required

Custom or future elicitation action.Values beginning with _ are reserved for implementation-specific extensions. Unknown values that do not begin with _ are reserved for future ACP variants.

fs/read_text_file

Reads content from a text file in the client’s file system. Only available if the client advertises the fs.readTextFile capability. Allows the agent to access file contents within the client’s environment. See protocol docs: Client

ReadTextFileRequest

Request to read content from a text file. Only available if the client supports the fs.readTextFile capability. Type: Object Properties:

object | null

integer | null

Maximum number of lines to read.

Minimum: 0

integer | null

Line number to start reading from (1-based).

Minimum: 0

string

required

Absolute path to the file to read.

SessionId

required

The session ID for this request.

ReadTextFileResponse

Response containing the contents of a text file. Type: Object Properties:

object | null

string

required

Content payload returned by this response.

fs/write_text_file

Writes content to a text file in the client’s file system. Only available if the client advertises the fs.writeTextFile capability. Allows the agent to create or modify files within the client’s environment. See protocol docs: Client

WriteTextFileRequest

Request to write content to a text file. Only available if the client supports the fs.writeTextFile capability. Type: Object Properties:

object | null

string

required

The text content to write to the file.

string

required

Absolute path to the file to write.

SessionId

required

The session ID for this request.

WriteTextFileResponse

Response to fs/write_text_file Type: Object Properties:

object | null

mcp/connect

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Opens an MCP-over-ACP connection.

ConnectMcpRequest

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Request parameters for mcp/connect. Type: Object Properties:

object | null

McpServerAcpId

required

The ACP MCP server ID that was provided by the component declaring the MCP server.

ConnectMcpResponse

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Response to mcp/connect. Type: Object Properties:

object | null

McpConnectionId

required

The unique identifier for this MCP-over-ACP connection.

mcp/disconnect

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Closes an MCP-over-ACP connection.

DisconnectMcpRequest

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Request parameters for mcp/disconnect. Type: Object Properties:

object | null

McpConnectionId

required

The MCP-over-ACP connection to close.

DisconnectMcpResponse

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Response to mcp/disconnect. Type: Object Properties:

object | null

mcp/message

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Exchanges an MCP-over-ACP message.

MessageMcpNotification

object | null

McpConnectionId

required

The MCP-over-ACP connection this message is sent on.

string

required

The inner MCP method name.

object | null

Optional inner MCP params.If omitted or set to null, the inner MCP message has no params.

MessageMcpRequest

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Request parameters for mcp/message. Type: Object Properties:

object | null

McpConnectionId

required

The MCP-over-ACP connection this message is sent on.

string

required

The inner MCP method name.

object | null

Optional inner MCP params.If omitted or set to null, the inner MCP message has no params.

MessageMcpResponse

session/request_permission

Requests permission from the user for a tool call operation. Called by the agent when it needs user authorization before executing a potentially sensitive operation. The client should present the options to the user and return their decision. If the client cancels the prompt turn via session/cancel, it MUST respond to this request with RequestPermissionOutcome::Cancelled. See protocol docs: Requesting Permission

RequestPermissionRequest

Request for user permission to execute a tool call. Sent when the agent needs authorization before performing a sensitive operation. See protocol docs: Requesting Permission Type: Object Properties:

object | null

PermissionOption[]

required

Available permission options for the user to choose from.

SessionId

required

The session ID for this request.

ToolCallUpdate

required

Details about the tool call requiring permission.

RequestPermissionResponse

Response to a permission request. Type: Object Properties:

object | null

RequestPermissionOutcome

required

The user’s decision on the permission request.

session/update

Handles session update notifications from the agent. This is a notification endpoint (no response expected) that receives real-time updates about session progress, including message chunks, tool calls, and execution plans. Note: Clients SHOULD continue accepting tool call updates even after sending a session/cancel notification, as the agent may send final updates before responding with the cancelled stop reason. See protocol docs: Agent Reports Output

SessionNotification

Notification containing a session update from the agent. Used to stream real-time progress and results during prompt processing. See protocol docs: Agent Reports Output Type: Object Properties:

object | null

SessionId

required

The ID of the session this update pertains to.

SessionUpdate

required

The actual update content.

terminal/create

Executes a command in a new terminal Only available if the terminal Client capability is set to true. Returns a TerminalId that can be used with other terminal methods to get the current output, wait for exit, and kill the command. The TerminalId can also be used to embed the terminal in a tool call by using the ToolCallContent::Terminal variant. The Agent is responsible for releasing the terminal by using the terminal/release method. See protocol docs: Terminals

CreateTerminalRequest

Request to create a new terminal and execute a command. Type: Object Properties:

object | null

"string"[]

Array of command arguments.

string

required

The command to execute.

string | null

Working directory for the command. Must be an absolute path.

EnvVariable[]

Environment variables for the command.

integer | null

Maximum number of output bytes to retain.When the limit is exceeded, the Client truncates from the beginning of the output to stay within the limit.The Client MUST ensure truncation happens at a character boundary to maintain valid string output, even if this means the retained output is slightly less than the specified limit.

Minimum: 0

SessionId

required

The session ID for this request.

CreateTerminalResponse

Response containing the ID of the created terminal. Type: Object Properties:

object | null

TerminalId

required

The unique identifier for the created terminal.

terminal/kill

Kills the terminal command without releasing the terminal While terminal/release will also kill the command, this method will keep the TerminalId valid so it can be used with other methods. This method can be helpful when implementing command timeouts which terminate the command as soon as elapsed, and then get the final output so it can be sent to the model. Note: Call terminal/release when TerminalId is no longer needed. See protocol docs: Terminals

KillTerminalRequest

Request to kill a terminal without releasing it. Type: Object Properties:

object | null

SessionId

required

The session ID for this request.

TerminalId

required

The ID of the terminal to kill.

KillTerminalResponse

Response to terminal/kill method Type: Object Properties:

object | null

terminal/output

Gets the terminal output and exit status Returns the current content in the terminal without waiting for the command to exit. If the command has already exited, the exit status is included. See protocol docs: Terminals

TerminalOutputRequest

Request to get the current output and status of a terminal. Type: Object Properties:

object | null

SessionId

required

The session ID for this request.

TerminalId

required

The ID of the terminal to get output from.

TerminalOutputResponse

Response containing the terminal output and exit status. Type: Object Properties:

object | null

TerminalExitStatus | null

Exit status if the command has completed.

string

required

The terminal output captured so far.

boolean

required

Whether the output was truncated due to byte limits.

terminal/release

Releases a terminal The command is killed if it hasn’t exited yet. Use terminal/wait_for_exit to wait for the command to exit before releasing the terminal. After release, the TerminalId can no longer be used with other terminal/* methods, but tool calls that already contain it, continue to display its output. The terminal/kill method can be used to terminate the command without releasing the terminal, allowing the Agent to call terminal/output and other methods. See protocol docs: Terminals

ReleaseTerminalRequest

Request to release a terminal and free its resources. Type: Object Properties:

object | null

SessionId

required

The session ID for this request.

TerminalId

required

The ID of the terminal to release.

ReleaseTerminalResponse

Response to terminal/release method Type: Object Properties:

object | null

terminal/wait_for_exit

Waits for the terminal command to exit and return its exit status See protocol docs: Terminals

WaitForTerminalExitRequest

Request to wait for a terminal command to exit. Type: Object Properties:

object | null

SessionId

required

The session ID for this request.

TerminalId

required

The ID of the terminal to wait for.

WaitForTerminalExitResponse

Response containing the exit status of a terminal command. Type: Object Properties:

object | null

integer | null

The process exit code (may be null if terminated by signal).

Minimum: 0

string | null

The signal that terminated the process (may be null if exited normally).

Protocol Level

Defines the interface that ACP-compliant agents and clients must both implement. Notifications whose methods start with ‘

/' are messages which are protocol implementation dependent and might not be implementable in all clients or agents. For example if the implementation uses a single threaded synchronous programming language then there is little it can do to react to a `

/cancel_request` notification. If an agent or client receives notifications starting with ’$/’ it is free to ignore the notification.

$/cancel_request

Cancels an ongoing request. This is a notification sent by the side that sent a request to cancel that request. Upon receiving this notification, the receiver:

MAY cancel the corresponding request activity and all nested activities
MAY send any pending notifications.
MUST send one of these responses for the original request:

Valid response with appropriate data (partial results or cancellation marker)
Error response with code -32800 (Cancelled)

See protocol docs: Cancellation

CancelRequestNotification

Notification to cancel an ongoing request. See protocol docs: Cancellation Type: Object Properties:

object | null

RequestId

required

The ID of the request to cancel.

AgentAuthCapabilities

Authentication-related capabilities supported by the agent. Type: Object Properties:

object | null

LogoutCapabilities | null

Whether the agent supports the logout method.Optional. Omitted or null both mean the agent does not advertise support. Supplying \{\} means the agent supports the logout method.

AgentCapabilities

Capabilities supported by the agent. Advertised during initialization to inform the client about available features and content types. See protocol docs: Agent Capabilities Type: Object Properties:

object | null

AgentAuthCapabilities

Authentication-related capabilities supported by the agent.

Default: {}

boolean

Whether the agent supports session/load.

Default: false

McpCapabilities

MCP capabilities supported by the agent.

Default: {"http":false,"sse":false,"acp":false}

NesCapabilities | null

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.NES (Next Edit Suggestions) capabilities supported by the agent.Optional. Omitted or null both mean the agent does not advertise support for NES methods.

PositionEncodingKind | null

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.The position encoding selected by the agent from the client’s supported encodings.

PromptCapabilities

Prompt capabilities supported by the agent.

Default: {"image":false,"audio":false,"embeddedContext":false}

ProvidersCapabilities | null

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.Provider configuration capabilities supported by the agent.Optional. Omitted or null both mean the agent does not advertise support. Supplying \{\} means the agent supports provider configuration methods.

SessionCapabilities

Session lifecycle and prompt capabilities advertised by the agent.

Default: {}

Annotations

Optional annotations for the client. The client can use annotations to inform how objects are used or displayed Type: Object Properties:

object | null

Role[] | null

Intended recipients for this content, such as the user or assistant.

string | null

Timestamp indicating when the underlying resource was last modified.

number | null

Relative importance of this content when clients choose what to surface.

AudioContent

Audio provided to or from an LLM. Type: Object Properties:

object | null

Annotations | null

Optional annotations that help clients decide how to display or route this content.

string

required

Base64-encoded media payload.

string

required

MIME type describing the encoded media payload.

AuthCapabilities

Authentication capabilities supported by the client. Advertised during initialization to inform the agent which authentication method types the client can handle. This governs opt-in types that require additional client-side support. Type: Object Properties:

object | null

boolean

Whether the client supports terminal authentication methods.The client should set this to true only when it can reproduce the configured agent invocation in an interactive terminal. When true, the agent may include terminal entries in its authentication methods.

Default: false

AuthMethod

Describes an available authentication method. The type field acts as the discriminator in the serialized JSON form. When no type is present, the method is treated as agent. Type: Union

object

Client runs the configured agent program as a separate interactive process, without passing this method to authenticate.

Show Properties

object | null

"string"[]

Additional arguments to append to the configured agent invocation for terminal auth.

string | null

Optional description providing more details about this authentication method.

object

Additional environment variables to set on the configured agent invocation for terminal auth. These values override same-named variables in the base launch configuration.

AuthMethodId

required

Unique identifier for this authentication method.

string

required

Human-readable name of the authentication method.

string

required

The discriminator value. Must be "terminal".

Agent handles authentication itself through authenticate.This is the default when no type is specified.

Show Properties

object | null

string | null

Optional description providing more details about this authentication method.

AuthMethodId

required

Unique identifier for this authentication method.

string

required

Human-readable name of the authentication method.

AuthMethodAgent

Agent handles authentication itself through authenticate. This is the default authentication method type. Type: Object Properties:

object | null

string | null

Optional description providing more details about this authentication method.

AuthMethodId

required

Unique identifier for this authentication method.

string

required

Human-readable name of the authentication method.

AuthMethodId

Typed identifier used for auth method values on the wire. Type: string

AuthMethodTerminal

Terminal-based authentication method. The client runs the configured agent program as a separate interactive process for the user to authenticate via a TUI. Agents MUST advertise this method only when the client enabled its terminal authentication capability. A zero exit status signals success; any other termination signals failure. The client MUST NOT pass this method to authenticate. Type: Object Properties:

object | null

"string"[]

Additional arguments to append to the configured agent invocation for terminal auth.

string | null

Optional description providing more details about this authentication method.

object

Additional environment variables to set on the configured agent invocation for terminal auth. These values override same-named variables in the base launch configuration.

AuthMethodId

required

Unique identifier for this authentication method.

string

required

Human-readable name of the authentication method.

AvailableCommand

Information about a command. Type: Object Properties:

object | null

string

required

Human-readable description of what the command does.

AvailableCommandInput | null

Input for the command if required

string

required

Command name (e.g., create_plan, research_codebase).

AvailableCommandInput

The input specification for a command. All text that was typed after the command name is provided as input. Type: Object Properties:

object | null

string

required

A hint to display when the input hasn’t been provided yet

AvailableCommandsUpdate

Available commands are ready or have changed Type: Object Properties:

object | null

AvailableCommand[]

required

Commands the agent can execute

BlobResourceContents

Binary resource contents. Type: Object Properties:

object | null

string

required

Base64-encoded bytes for a binary resource payload.

string | null

MIME type describing the encoded media payload.

string

required

URI associated with this resource or media payload.

BooleanConfigOptionCapabilities

Capabilities for boolean session configuration options. Supplying \{\} means the client supports boolean session configuration options. Type: Object Properties:

object | null

BooleanPropertySchema

Schema for boolean properties in an elicitation form. Type: Object Properties:

object | null

boolean | null

Default value.Optional. Omitted and null are equivalent and mean no default value is provided.

string | null

Human-readable description.Optional. Omitted and null are equivalent and mean no description is provided.

string | null

Optional title for the property.Optional. Omitted and null are equivalent and mean no title is provided.

ClientCapabilities

Capabilities supported by the client. Advertised during initialization to inform the agent about available features and methods. See protocol docs: Client Capabilities Type: Object Properties:

object | null

AuthCapabilities

Authentication capabilities supported by the client. Determines which authentication method types the agent may include in its InitializeResponse.

Default: {"terminal":false}

ElicitationCapabilities | null

Elicitation capabilities supported by the client. Determines which elicitation modes the agent may use.Optional. Omitted or null both mean the client does not advertise elicitation support.

FileSystemCapabilities

File system capabilities supported by the client. Determines which file operations the agent can request.

Default: {"readTextFile":false,"writeTextFile":false}

ClientNesCapabilities | null

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.NES (Next Edit Suggestions) capabilities supported by the client.Optional. Omitted or null both mean the client does not advertise any NES suggestion-kind extensions.

PlanCapabilities | null

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.Whether the client supports plan_update and plan_removed session updates.Optional. Omitted or null both mean the client does not advertise support. Supplying \{\} means the client can receive both update types.

PositionEncodingKind[]

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.The position encodings supported by the client, in order of preference.

ClientSessionCapabilities | null

Session-related capabilities supported by the client.Optional. Omitted or null both mean the client does not advertise any session-related extensions.

boolean

Whether the Client support all terminal/* methods.

Default: false

ClientNesCapabilities

NES capabilities advertised by the client during initialization. Type: Object Properties:

object | null

NesJumpCapabilities | null

Whether the client supports the jump suggestion kind.

NesRenameCapabilities | null

Whether the client supports the rename suggestion kind.

NesSearchAndReplaceCapabilities | null

Whether the client supports the searchAndReplace suggestion kind.

ClientSessionCapabilities

Session-related capabilities supported by the client. Type: Object Properties:

object | null

CompactionCapabilities | null

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.Support for ID-addressed context compaction updates. Omitted or null means unsupported; \{\} advertises the complete compaction contract.

SessionConfigOptionsCapabilities | null

Config option capabilities supported by the client.Omitted or null both mean the client does not advertise support for any config option extensions.

CompactionCapabilities

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Client support for ID-addressed context compaction updates. Type: object

CompactionId

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Unique identifier for a context compaction within a session. Type: string

CompactionStatus

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Lifecycle state of a context compaction. Type: Union

string

Compaction has started and has not finished.

string

Compaction finished successfully.

string

Compaction finished unsuccessfully.

string

Compaction was cancelled before it finished.

string

Custom or future compaction status.Values beginning with _ are reserved for implementation-specific extensions. Other unknown values are reserved for future ACP statuses.

CompactionSummaryChunk

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. A content block appended to the retained summary of an in-progress compaction. Agents send chunks only after an in_progress update and before the terminal update for the same ID. Agents MUST only send this update when the Client advertised ClientSessionCapabilities::compaction. Type: Object Properties:

object | null

Metadata scoped to this chunk. Omission and null both mean absent.

CompactionId

required

ID of the compaction whose summary receives this content.

ContentBlock

required

One content block to append.

CompactionUpdate

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. A context compaction upsert. The first update fixes the compaction’s timeline position. Later updates with the same ID patch that entity in place. Agents MUST only send this update when the Client advertised ClientSessionCapabilities::compaction. summary, error, and _meta have patch semantics: omission leaves the stored value unchanged, null clears it, and a concrete value replaces it. summary: [] also clears the retained summary. A non-empty summary is only valid with completed; error is only valid with failed. Type: Object Properties:

object | null

Extensible metadata patch for this compaction.

CompactionId

required

The Agent-owned ID of this compaction, unique within the session.

string | null

Human-readable description of why the compaction failed.

CompactionStatus

required

Current lifecycle status.

ContentBlock[] | null

Complete replacement user-displayable summary retained by the compaction.

ConfigOptionUpdate

Session configuration options have been updated. Type: Object Properties:

object | null

SessionConfigOption[]

required

The full set of configuration options and their current values.

Content

Standard content block (text, images, resources). Type: Object Properties:

object | null

ContentBlock

required

The actual content block.

ContentBlock

Content blocks represent displayable information in the Agent Client Protocol. They provide a structured way to handle various types of user-facing content—whether it’s text from language models, images for analysis, or embedded resources for context. Content blocks appear in:

User prompts sent via session/prompt
Language model output streamed through session/update notifications
Progress updates and results from tool calls

This structure is compatible with the Model Context Protocol (MCP), enabling agents to seamlessly forward content from MCP tool outputs without transformation. See protocol docs: Content Type: Union

object

Text content. May be plain text or formatted with Markdown.All agents MUST support text content blocks in prompts. Clients SHOULD render this text as Markdown.

Show Properties

object | null

Annotations | null

Optional annotations that help clients decide how to display or route this content.

string

required

Text payload carried by this content block.

string

required

The discriminator value. Must be "text".

object

Images for visual context or analysis.Requires the image prompt capability when included in prompts.

Show Properties

object | null

Annotations | null

Optional annotations that help clients decide how to display or route this content.

string

required

Base64-encoded media payload.

string

required

MIME type describing the encoded media payload.

string

required

The discriminator value. Must be "image".

string | null

URI associated with this resource or media payload.

object

Audio data for transcription or analysis.Requires the audio prompt capability when included in prompts.

Show Properties

object | null

Annotations | null

Optional annotations that help clients decide how to display or route this content.

string

required

Base64-encoded media payload.

string

required

MIME type describing the encoded media payload.

string

required

The discriminator value. Must be "audio".

object

References to resources that the agent can access.All agents MUST support resource links in prompts.

Show Properties

object | null

Annotations | null

Optional annotations that help clients decide how to display or route this content.

string | null

Optional human-readable details shown with this protocol object.

string | null

MIME type describing the encoded media payload.

string

required

Human-readable name shown for this protocol object.

integer | null

Optional size of the linked resource in bytes, if known.

string | null

Optional display title for end-user UI.

string

required

The discriminator value. Must be "resource_link".

string

required

URI associated with this resource or media payload.

object

Complete resource contents embedded directly in the message.Preferred for including context as it avoids extra round-trips.Requires the embeddedContext prompt capability when included in prompts.

Show Properties

object | null

Annotations | null

Optional annotations that help clients decide how to display or route this content.

EmbeddedResourceResource

required

Embedded resource payload, either text or binary data.

string

required

The discriminator value. Must be "resource".

ContentChunk

A streamed item of content Type: Object Properties:

object | null

ContentBlock

required

A single item of content

MessageId | null

A unique identifier for the message this chunk belongs to.All chunks belonging to the same message share the same messageId. A change in messageId indicates a new message has started.

Cost

Cost information for a session. Type: Object Properties:

object | null

number

required

Total cumulative cost for session.

string

required

ISO 4217 currency code (e.g., “USD”, “EUR”).

CurrentModeUpdate

The current mode of the session has changed See protocol docs: Session Modes Type: Object Properties:

object | null

SessionModeId

required

The ID of the current mode

Diff

A diff representing file modifications. Shows changes to files in a format suitable for display in the client UI. See protocol docs: Content Type: Object Properties:

object | null

string

required

The new content after modification.

string | null

The original content (None for new files).

string

required

The absolute file path being modified.

ElicitationAcceptAction

The user accepted the elicitation and provided content. Type: Object Properties:

object | null

The user-provided content, if any, as an object matching the requested schema.

ElicitationCapabilities

Elicitation capabilities supported by the client. Type: Object Properties:

object | null

ElicitationFormCapabilities | null

Whether the client supports form-based elicitation.Optional. Omitted and null are equivalent and mean form support is not advertised. Supplying \{\} explicitly advertises form support.

ElicitationUrlCapabilities | null

Whether the client supports URL-based elicitation.Optional. Omitted or null both mean the client does not advertise support. Supplying \{\} means the client supports URL-based elicitation.

ElicitationContentValue

Allowed wire representations for ElicitationContentValue. Type: Union

string

String value accepted in elicitation response content.

int64

Integer value accepted in elicitation response content.

double

Number value accepted in elicitation response content.

boolean

Boolean value accepted in elicitation response content.

array

String array value accepted in elicitation response content.

ElicitationFormCapabilities

Form-based elicitation capabilities. Supplying \{\} means the client supports form-based elicitation. Type: Object Properties:

object | null

ElicitationFormMode

Form-based elicitation mode where the client renders a form from the provided schema. Type: Union Shared properties:

ElicitationSchema

required

A JSON Schema describing the form fields to present to the user.

Variants:

Tied to a session, optionally to a specific tool call within that session.

Show Properties

SessionId

required

The session this elicitation is tied to.

ToolCallId | null

Optional tool call within the session.Optional. Omitted and null are equivalent and mean the elicitation is scoped to the session without a specific tool call.

Tied to a specific JSON-RPC request outside of a session (e.g., during auth/configuration phases before any session is started).

Show Properties

RequestId

required

The request this elicitation is tied to.

ElicitationId

Unique identifier for an elicitation. Type: string

ElicitationPropertySchema

Property schema for elicitation form fields. Each variant corresponds to a JSON Schema "type" value. Single-select enums use the String variant with enum or oneOf set. Multi-select enums use the Array variant. Type: Union

object

String property (or single-select enum when enum/oneOf is set).

Show Properties

object | null

string | null

Default value.Optional. Omitted and null are equivalent and mean no default value is provided.

string | null

Human-readable description.Optional. Omitted and null are equivalent and mean no description is provided.

"string"[] | null

Enum values for untitled single-select enums. Optional. Omitted and null are equivalent and mean no untitled single-select choices are declared by enum.

StringFormat | null

String format.Optional. Omitted and null are equivalent and mean there is no format constraint.

integer | null

Maximum string length.Optional. Omitted and null are equivalent and mean there is no maximum length constraint.

Minimum: 0

integer | null

Minimum string length.Optional. Omitted and null are equivalent and mean there is no minimum length constraint.

Minimum: 0

EnumOption[] | null

Titled enum options for titled single-select enums. Optional. Omitted and null are equivalent and mean no titled single-select choices are declared by oneOf.

string | null

Pattern the string must match.Optional. Omitted and null are equivalent and mean there is no pattern constraint.

string | null

Optional title for the property.Optional. Omitted and null are equivalent and mean no title is provided.

string

required

The discriminator value. Must be "string".

object

Number (floating-point) property.

Show Properties

object | null

number | null

Default value.Optional. Omitted and null are equivalent and mean no default value is provided.

string | null

Human-readable description.Optional. Omitted and null are equivalent and mean no description is provided.

number | null

Maximum value (inclusive).Optional. Omitted and null are equivalent and mean there is no inclusive upper bound.

number | null

Minimum value (inclusive).Optional. Omitted and null are equivalent and mean there is no inclusive lower bound.

string | null

Optional title for the property.Optional. Omitted and null are equivalent and mean no title is provided.

string

required

The discriminator value. Must be "number".

object

Integer property.

Show Properties

object | null

integer | null

Default value.Optional. Omitted and null are equivalent and mean no default value is provided.

string | null

Human-readable description.Optional. Omitted and null are equivalent and mean no description is provided.

integer | null

Maximum value (inclusive).Optional. Omitted and null are equivalent and mean there is no inclusive upper bound.

integer | null

Minimum value (inclusive).Optional. Omitted and null are equivalent and mean there is no inclusive lower bound.

string | null

Optional title for the property.Optional. Omitted and null are equivalent and mean no title is provided.

string

required

The discriminator value. Must be "integer".

object

Boolean property.

Show Properties

object | null

boolean | null

Default value.Optional. Omitted and null are equivalent and mean no default value is provided.

string | null

Human-readable description.Optional. Omitted and null are equivalent and mean no description is provided.

string | null

Optional title for the property.Optional. Omitted and null are equivalent and mean no title is provided.

string

required

The discriminator value. Must be "boolean".

object

Multi-select array property.

Show Properties

object | null

"string"[] | null

Default selected values.Optional. Omitted and null are equivalent and mean no default selections are provided.

string | null

Human-readable description.Optional. Omitted and null are equivalent and mean no description is provided.

MultiSelectItems

required

The items definition describing allowed values.

integer | null

Maximum number of items to select.Optional. Omitted and null are equivalent and mean there is no maximum selection count.

Minimum: 0

integer | null

Minimum number of items to select.Optional. Omitted and null are equivalent and mean there is no minimum selection count.

Minimum: 0

string | null

Optional title for the property.Optional. Omitted and null are equivalent and mean no title is provided.

string

required

The discriminator value. Must be "array".

object

Custom or future elicitation property schema.Values beginning with _ are reserved for implementation-specific extensions. Unknown values that do not begin with _ are reserved for future ACP variants.Clients that do not understand this property schema type should preserve the raw schema when storing, replaying, proxying, or forwarding elicitation requests. They MUST NOT render it as a known input control.

Show Properties

string

required

Custom or future elicitation property schema type.Values beginning with _ are reserved for implementation-specific extensions. Unknown values that do not begin with _ are reserved for future ACP variants.

ElicitationRequestScope

Request-scoped elicitation, tied to a specific JSON-RPC request outside of a session (e.g., during auth/configuration phases before any session is started). Type: Object Properties:

RequestId

required

The request this elicitation is tied to.

ElicitationSchema

Type-safe elicitation schema for requesting structured user input. This represents a JSON Schema object with primitive-typed properties, as required by the elicitation specification. Type: Object Properties:

object | null

string | null

Optional description of what this schema represents.Optional. Omitted and null are equivalent and mean no schema description is provided.

object

Property definitions (must be primitive types).

Default: {}

"string"[] | null

List of required property names.Optional. Omitted and null are equivalent and mean no property names are required.

string | null

Optional title for the schema.Optional. Omitted and null are equivalent and mean no title is provided.

ElicitationSchemaType

Type discriminator. Always "object".

Default: "object"

ElicitationSchemaType

Type discriminator for elicitation schemas. Type: Union

string

Object schema type.

ElicitationSessionScope

Session-scoped elicitation, optionally tied to a specific tool call. When tool_call_id is set, the elicitation is tied to a specific tool call. This is useful when an agent receives an elicitation from an MCP server during a tool call and needs to redirect it to the user. Type: Object Properties:

SessionId

required

The session this elicitation is tied to.

ToolCallId | null

Optional tool call within the session.Optional. Omitted and null are equivalent and mean the elicitation is scoped to the session without a specific tool call.

ElicitationUrlCapabilities

URL-based elicitation capabilities. Supplying \{\} means the client supports URL-based elicitation. Type: Object Properties:

object | null

ElicitationUrlMode

URL-based elicitation mode where the client directs the user to a URL. Type: Union Shared properties:

ElicitationId

required

The unique identifier for this elicitation.

string

required

The URL to direct the user to.

Format: uri

Variants:

Tied to a session, optionally to a specific tool call within that session.

Show Properties

SessionId

required

The session this elicitation is tied to.

ToolCallId | null

Optional tool call within the session.Optional. Omitted and null are equivalent and mean the elicitation is scoped to the session without a specific tool call.

Tied to a specific JSON-RPC request outside of a session (e.g., during auth/configuration phases before any session is started).

Show Properties

RequestId

required

The request this elicitation is tied to.

EmbeddedResource

The contents of a resource, embedded into a prompt or tool call result. Type: Object Properties:

object | null

Annotations | null

Optional annotations that help clients decide how to display or route this content.

EmbeddedResourceResource

required

Embedded resource payload, either text or binary data.

EmbeddedResourceResource

Resource content that can be embedded in a message. Type: Union

Text resource contents embedded directly in the message.

Show Properties

object | null

string | null

MIME type describing the encoded media payload.

string

required

Text payload carried by this content block.

string

required

URI associated with this resource or media payload.

Binary resource contents embedded directly in the message.

Show Properties

object | null

string

required

Base64-encoded bytes for a binary resource payload.

string | null

MIME type describing the encoded media payload.

string

required

URI associated with this resource or media payload.

EnumOption

A titled enum option with a const value, human-readable title, and optional description. Type: Object Properties:

object | null

string

required

The constant value for this option.

string | null

Human-readable description.Optional. Omitted and null are equivalent and mean no description is provided.

string

required

Human-readable title for this option.

EnvVariable

An environment variable to set when launching an MCP server. Type: Object Properties:

object | null

string

required

The name of the environment variable.

string

required

The value to set for the environment variable.

Error

JSON-RPC error object. Represents an error that occurred during method execution, following the JSON-RPC 2.0 error object specification with optional additional data. See protocol docs: JSON-RPC Error Object Type: Object Properties:

ErrorCode

required

A number indicating the error type that occurred. This must be an integer as defined in the JSON-RPC specification.

object

Optional primitive or structured value that contains additional information about the error. This may include debugging information or context-specific details.

string

required

A string providing a short description of the error. The message should be limited to a concise single sentence.

ErrorCode

Predefined error codes for common JSON-RPC and ACP-specific errors. These codes follow the JSON-RPC 2.0 specification for standard errors and use the reserved range (-32000 to -32099) for protocol-specific errors. Type: Union

int32

Parse error: Invalid JSON was received by the server. An error occurred on the server while parsing the JSON text.

int32

Invalid request: The JSON sent is not a valid Request object.

int32

Method not found: The method does not exist or is not available.

int32

Invalid params: Invalid method parameter(s).

int32

Internal error: Internal JSON-RPC error. Reserved for implementation-defined server errors.

int32

Request cancelled: Execution of the method was aborted either due to a cancellation request from the caller or because of resource constraints or shutdown.

int32

Authentication required: Authentication is required before this operation can be performed.

int32

Resource not found: A given resource, such as a file, was not found.

int32

Other undefined error code.

ExtNotification

Allows the Agent to send an arbitrary notification that is not part of the ACP spec. Extension notifications provide a way to send one-way messages for custom functionality while maintaining protocol compatibility. See protocol docs: Extensibility

ExtRequest

Allows for sending an arbitrary request that is not part of the ACP spec. Extension methods provide a way to add custom functionality while maintaining protocol compatibility. See protocol docs: Extensibility

ExtResponse

Allows for sending an arbitrary response to an ExtRequest that is not part of the ACP spec. Extension methods provide a way to add custom functionality while maintaining protocol compatibility. See protocol docs: Extensibility

FileSystemCapabilities

File system capabilities that a client may support. See protocol docs: FileSystem Type: Object Properties:

object | null

boolean

Whether the Client supports fs/read_text_file requests.

Default: false

boolean

Whether the Client supports fs/write_text_file requests.

Default: false

HttpHeader

An HTTP header to set when making requests to the MCP server. Type: Object Properties:

object | null

string

required

The name of the HTTP header.

string

required

The value to set for the HTTP header.

ImageContent

An image provided to or from an LLM. Type: Object Properties:

object | null

Annotations | null

Optional annotations that help clients decide how to display or route this content.

string

required

Base64-encoded media payload.

string

required

MIME type describing the encoded media payload.

string | null

URI associated with this resource or media payload.

Implementation

Metadata about the implementation of the client or agent. Describes the name and version of an ACP implementation, with an optional title for UI representation. Type: Object Properties:

object | null

string

required

Intended for programmatic or logical use, but can be used as a display name fallback if title isn’t present.

string | null

Intended for UI and end-user contexts — optimized to be human-readable and easily understood.If not provided, the name should be used for display.

string

required

Version of the implementation. Can be displayed to the user or used for debugging or metrics purposes. (e.g. “1.0.0”).

IntegerPropertySchema

Schema for integer properties in an elicitation form. Type: Object Properties:

object | null

integer | null

Default value.Optional. Omitted and null are equivalent and mean no default value is provided.

string | null

Human-readable description.Optional. Omitted and null are equivalent and mean no description is provided.

integer | null

Maximum value (inclusive).Optional. Omitted and null are equivalent and mean there is no inclusive upper bound.

integer | null

Minimum value (inclusive).Optional. Omitted and null are equivalent and mean there is no inclusive lower bound.

string | null

Optional title for the property.Optional. Omitted and null are equivalent and mean no title is provided.

LlmProtocol

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Well-known API protocol identifiers for LLM providers. Agents and clients MUST handle unknown protocol identifiers gracefully. Protocol names beginning with _ are free for custom use, like other ACP extension methods. Protocol names that do not begin with _ are reserved for the ACP spec. Type: Union

string

Anthropic API protocol.

string

OpenAI API protocol.

string

Azure OpenAI API protocol.

string

Google Vertex AI API protocol.

string

AWS Bedrock API protocol.

string

Unknown or custom protocol.

LogoutCapabilities

Logout capabilities supported by the agent. Supplying \{\} means the agent supports the logout method. Type: Object Properties:

object | null

McpCapabilities

MCP capabilities supported by the agent Type: Object Properties:

object | null

boolean

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.Agent supports McpServer::Acp.

Default: false

boolean

Agent supports McpServer::Http.

Default: false

boolean

Agent supports McpServer::Sse.

Default: false

McpConnectionId

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. A unique identifier for an active MCP-over-ACP connection. Type: string

McpServer

Configuration for connecting to an MCP (Model Context Protocol) server. MCP servers provide tools and context that the agent can use when processing prompts. See protocol docs: MCP Servers Type: Union

object

HTTP transport configurationOnly available when the Agent capabilities indicate mcp_capabilities.http is true.

Show Properties

object | null

HttpHeader[]

required

HTTP headers to set when making requests to the MCP server.

string

required

Human-readable name identifying this MCP server.

string

required

The discriminator value. Must be "http".

string

required

URL to the MCP server.

object

SSE transport configurationOnly available when the Agent capabilities indicate mcp_capabilities.sse is true.

Show Properties

object | null

HttpHeader[]

required

HTTP headers to set when making requests to the MCP server.

string

required

Human-readable name identifying this MCP server.

string

required

The discriminator value. Must be "sse".

string

required

URL to the MCP server.

object

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.ACP transport configurationOnly available when the Agent capabilities indicate mcp_capabilities.acp is true. The MCP server is provided by an ACP component and communicates over the ACP channel.

Show Properties

object | null

string

required

Human-readable name identifying this MCP server.

McpServerAcpId

required

Unique identifier for this MCP server, generated by the component providing it.Providers MUST NOT reuse an ID for multiple ACP-transport MCP servers that are visible on the same ACP connection.

string

required

The discriminator value. Must be "acp".

Stdio transport configurationAll Agents MUST support this transport.

Show Properties

object | null

"string"[]

required

Command-line arguments to pass to the MCP server.

string

required

Absolute path to the MCP server executable.

EnvVariable[]

required

Environment variables to set when launching the MCP server.

string

required

Human-readable name identifying this MCP server.

McpServerAcp

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. ACP transport configuration for MCP. The MCP server is provided by an ACP component and communicates over the ACP channel using mcp/connect, mcp/message, and mcp/disconnect. Type: Object Properties:

object | null

string

required

Human-readable name identifying this MCP server.

McpServerAcpId

required

Unique identifier for this MCP server, generated by the component providing it.Providers MUST NOT reuse an ID for multiple ACP-transport MCP servers that are visible on the same ACP connection.

McpServerAcpId

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Unique identifier for an MCP server using the ACP transport. The value is opaque and generated by the ACP component providing the MCP server. It is used by mcp/connect to route connection requests back to the component that declared the server. Type: string

McpServerHttp

HTTP transport configuration for MCP. Type: Object Properties:

object | null

HttpHeader[]

required

HTTP headers to set when making requests to the MCP server.

string

required

Human-readable name identifying this MCP server.

string

required

URL to the MCP server.

McpServerSse

SSE transport configuration for MCP. Type: Object Properties:

object | null

HttpHeader[]

required

HTTP headers to set when making requests to the MCP server.

string

required

Human-readable name identifying this MCP server.

string

required

URL to the MCP server.

McpServerStdio

Stdio transport configuration for MCP. Type: Object Properties:

object | null

"string"[]

required

Command-line arguments to pass to the MCP server.

string

required

Absolute path to the MCP server executable.

EnvVariable[]

required

Environment variables to set when launching the MCP server.

string

required

Human-readable name identifying this MCP server.

MessageId

Unique identifier for a message within a session. Type: string

MultiSelectItems

Items for a multi-select (array) property schema. Type: Union

object

Multi-select string items with plain string values.

Show Properties

object | null

"string"[]

required

Allowed enum values.

string

required

The discriminator value. Must be "string".

object

Custom or future typed multi-select items.

Show Properties

string

required

Custom or future multi-select item type.Values beginning with _ are reserved for implementation-specific extensions. Unknown values that do not begin with _ are reserved for future ACP variants.

Titled multi-select items with human-readable labels.

Show Properties

object | null

EnumOption[]

required

Titled enum options.

MultiSelectPropertySchema

Schema for multi-select (array) properties in an elicitation form. Type: Object Properties:

object | null

"string"[] | null

Default selected values.Optional. Omitted and null are equivalent and mean no default selections are provided.

string | null

Human-readable description.Optional. Omitted and null are equivalent and mean no description is provided.

MultiSelectItems

required

The items definition describing allowed values.

integer | null

Maximum number of items to select.Optional. Omitted and null are equivalent and mean there is no maximum selection count.

Minimum: 0

integer | null

Minimum number of items to select.Optional. Omitted and null are equivalent and mean there is no minimum selection count.

Minimum: 0

string | null

Optional title for the property.Optional. Omitted and null are equivalent and mean no title is provided.

NesCapabilities

NES capabilities advertised by the agent during initialization. Type: Object Properties:

object | null

NesContextCapabilities | null

Context the agent wants attached to each suggestion request.

NesEventCapabilities | null

Events the agent wants to receive.

NesContextCapabilities

Context capabilities the agent wants attached to each suggestion request. Type: Object Properties:

object | null

NesDiagnosticsCapabilities | null

Whether the agent wants diagnostics context.

NesEditHistoryCapabilities | null

Whether the agent wants edit history context.

NesOpenFilesCapabilities | null

Whether the agent wants open files context.

NesRecentFilesCapabilities | null

Whether the agent wants recent files context.

Whether the agent wants related snippets context.

NesUserActionsCapabilities | null

Whether the agent wants user actions context.

NesDiagnostic

A diagnostic (error, warning, etc.). Type: Object Properties:

object | null

string

required

The diagnostic message.

Range

required

The range of the diagnostic.

NesDiagnosticSeverity

required

The severity of the diagnostic.

string

required

The URI of the file containing the diagnostic.

NesDiagnosticSeverity

Severity of a diagnostic. Type: Union

string

An error.

string

A warning.

string

An informational message.

string

A hint.

NesDiagnosticsCapabilities

Capabilities for diagnostics context. Type: Object Properties:

object | null

NesDocumentDidChangeCapabilities

Capabilities for document/didChange events. Type: Object Properties:

object | null

TextDocumentSyncKind

required

The sync kind the agent wants: "full" or "incremental".

NesDocumentDidCloseCapabilities

Marker for document/didClose capability support. Type: Object Properties:

object | null

NesDocumentDidFocusCapabilities

Marker for document/didFocus capability support. Type: Object Properties:

object | null

NesDocumentDidOpenCapabilities

Marker for document/didOpen capability support. Type: Object Properties:

object | null

NesDocumentDidSaveCapabilities

Marker for document/didSave capability support. Type: Object Properties:

object | null

NesDocumentEventCapabilities

Document event capabilities the agent wants to receive. Type: Object Properties:

object | null

NesDocumentDidChangeCapabilities | null

Whether the agent wants document/didChange events, and the sync kind.

NesDocumentDidCloseCapabilities | null

Whether the agent wants document/didClose events.

NesDocumentDidFocusCapabilities | null

Whether the agent wants document/didFocus events.

NesDocumentDidOpenCapabilities | null

Whether the agent wants document/didOpen events.

NesDocumentDidSaveCapabilities | null

Whether the agent wants document/didSave events.

NesEditHistoryCapabilities

Capabilities for edit history context. Type: Object Properties:

object | null

integer | null

Maximum number of edit history entries the agent can use.

Minimum: 0

NesEditHistoryEntry

An entry in the edit history. Type: Object Properties:

object | null

string

required

A diff representing the edit.

string

required

The URI of the edited file.

NesEditSuggestion

A text edit suggestion. Type: Object Properties:

object | null

Position | null

Optional suggested cursor position after applying edits.

NesTextEdit[]

required

The text edits to apply.

NesSuggestionId

required

Unique identifier for accept/reject tracking.

string

required

The URI of the file to edit.

NesEventCapabilities

Event capabilities the agent can consume. Type: Object Properties:

object | null

NesDocumentEventCapabilities | null

Document event capabilities.

NesExcerpt

A code excerpt from a file. Type: Object Properties:

object | null

uint32

required

The end line of the excerpt (zero-based).

Minimum: 0

uint32

required

The start line of the excerpt (zero-based).

Minimum: 0

string

required

The text content of the excerpt.

NesJumpCapabilities

Marker for jump suggestion support. Type: Object Properties:

object | null

NesJumpSuggestion

A jump-to-location suggestion. Type: Object Properties:

object | null

NesSuggestionId

required

Unique identifier for accept/reject tracking.

Position

required

The target position within the file.

string

required

The file to navigate to.

NesOpenFile

An open file in the editor. Type: Object Properties:

object | null

string

required

The language identifier.

integer | null

Timestamp in milliseconds since epoch of when the file was last focused.

Minimum: 0

string

required

The URI of the file.

Range | null

The visible range in the editor, if any.

NesOpenFilesCapabilities

Capabilities for open files context. Type: Object Properties:

object | null

NesRecentFile

A recently accessed file. Type: Object Properties:

object | null

string

required

The language identifier.

string

required

The full text content of the file.

string

required

The URI of the file.

NesRecentFilesCapabilities

Capabilities for recent files context. Type: Object Properties:

object | null

integer | null

Maximum number of recent files the agent can use.

Minimum: 0

NesRejectReason

The reason a suggestion was rejected. Type: Union

string

The user explicitly dismissed the suggestion.

string

The suggestion was shown but the user continued editing without interacting.

string

The suggestion was superseded by a newer suggestion.

string

The request was cancelled before the agent returned a response.

NesRelatedSnippet

A related code snippet from a file. Type: Object Properties:

object | null

NesExcerpt[]

required

The code excerpts.

string

required

The URI of the file containing the snippets.

NesRelatedSnippetsCapabilities

Capabilities for related snippets context. Type: Object Properties:

object | null

NesRenameCapabilities

Marker for rename suggestion support. Type: Object Properties:

object | null

NesRenameSuggestion

A rename symbol suggestion. Type: Object Properties:

object | null

NesSuggestionId

required

Unique identifier for accept/reject tracking.

string

required

The new name for the symbol.

Position

required

The position of the symbol to rename.

string

required

The file URI containing the symbol.

NesRepository

Repository metadata for an NES session. Type: Object Properties:

object | null

string

required

The repository name.

string

required

The repository owner.

string

required

The remote URL of the repository.

NesSearchAndReplaceCapabilities

Marker for search and replace suggestion support. Type: Object Properties:

object | null

NesSearchAndReplaceSuggestion

A search-and-replace suggestion. Type: Object Properties:

object | null

NesSuggestionId

required

Unique identifier for accept/reject tracking.

boolean | null

Whether search is a regular expression. Defaults to false.

string

required

The replacement text.

string

required

The text or pattern to find.

string

required

The file URI to search within.

NesSuggestContext

Context attached to a suggestion request. Type: Object Properties:

object | null

NesDiagnostic[] | null

Current diagnostics (errors, warnings).

NesEditHistoryEntry[] | null

Recent edit history.

NesOpenFile[] | null

Currently open files in the editor.

NesRecentFile[] | null

Recently accessed files.

Related code snippets.

NesUserAction[] | null

Recent user actions (typing, navigation, etc.).

NesSuggestion

A suggestion returned by the agent. Type: Union

object

A text edit suggestion.

Show Properties

object | null

Position | null

Optional suggested cursor position after applying edits.

NesTextEdit[]

required

The text edits to apply.

NesSuggestionId

required

Unique identifier for accept/reject tracking.

string

required

The discriminator value. Must be "edit".

string

required

The URI of the file to edit.

object

A jump-to-location suggestion.

Show Properties

object | null

NesSuggestionId

required

Unique identifier for accept/reject tracking.

string

required

The discriminator value. Must be "jump".

Position

required

The target position within the file.

string

required

The file to navigate to.

object

A rename symbol suggestion.

Show Properties

object | null

NesSuggestionId

required

Unique identifier for accept/reject tracking.

string

required

The discriminator value. Must be "rename".

string

required

The new name for the symbol.

Position

required

The position of the symbol to rename.

string

required

The file URI containing the symbol.

object

A search-and-replace suggestion.

Show Properties

object | null

NesSuggestionId

required

Unique identifier for accept/reject tracking.

boolean | null

Whether search is a regular expression. Defaults to false.

string

required

The discriminator value. Must be "searchAndReplace".

string

required

The replacement text.

string

required

The text or pattern to find.

string

required

The file URI to search within.

NesSuggestionId

Unique identifier for a next edit suggestion. Type: string

NesTextEdit

A text edit within a suggestion. Type: Object Properties:

object | null

string

required

The replacement text.

Range

required

The range to replace.

NesTriggerKind

What triggered the suggestion request. Type: Union

string

Triggered by user typing or cursor movement.

string

Triggered by a diagnostic appearing at or near the cursor.

string

Triggered by an explicit user action (keyboard shortcut).

NesUserAction

A user action (typing, cursor movement, etc.). Type: Object Properties:

object | null

string

required

The kind of action (e.g., “insertChar”, “cursorMovement”).

Position

required

The position where the action occurred.

uint64

required

Timestamp in milliseconds since epoch.

Minimum: 0

string

required

The URI of the file where the action occurred.

NesUserActionsCapabilities

Capabilities for user actions context. Type: Object Properties:

object | null

integer | null

Maximum number of user actions the agent can use.

Minimum: 0

Notice

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Fire-and-forget advisory information for the user. Notices are live events rather than session history. Agents must not rely on a notice being received, displayed, or seen by the user. No Client capability is required, and unsupported Clients may ignore notices. See RFD: Session Notices Type: Object Properties:

object | null

Metadata scoped to this notice.Omitted and null are equivalent and mean no metadata was supplied.

string | null

Optional plain-text detail or guidance.Omitted and null are equivalent and mean no description was supplied.

NoticeSeverity

required

Presentation severity hint.

string

required

Required non-empty plain-text title that can stand alone.

Min length: 1

NoticeSeverity

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Severity hint for a session notice. Type: Union

string

Informational notice.

string

Warning notice.

string

Error notice.

string

Custom or future notice severity.Values beginning with _ are reserved for implementation-specific extensions. Other unknown values are reserved for future ACP severities.

NumberPropertySchema

Schema for number (floating-point) properties in an elicitation form. Type: Object Properties:

object | null

number | null

Default value.Optional. Omitted and null are equivalent and mean no default value is provided.

string | null

Human-readable description.Optional. Omitted and null are equivalent and mean no description is provided.

number | null

Maximum value (inclusive).Optional. Omitted and null are equivalent and mean there is no inclusive upper bound.

number | null

Minimum value (inclusive).Optional. Omitted and null are equivalent and mean there is no inclusive lower bound.

string | null

Optional title for the property.Optional. Omitted and null are equivalent and mean no title is provided.

PermissionOption

An option presented to the user when requesting permission. Type: Object Properties:

object | null

PermissionOptionKind

required

Hint about the nature of this permission option.

string

required

Human-readable label to display to the user.

PermissionOptionId

required

Unique identifier for this permission option.

PermissionOptionId

Unique identifier for a permission option. Type: string

PermissionOptionKind

The type of permission option being presented to the user. Helps clients choose appropriate icons and UI treatment. Type: Union

string

Allow this operation only this time.

string

Allow this operation and remember the choice.

string

Reject this operation only this time.

string

Reject this operation and remember the choice.

Plan

An execution plan for accomplishing complex tasks. Plans consist of multiple entries representing individual tasks or goals. Agents report plans to clients to provide visibility into their execution strategy. Plans can evolve during execution as the agent discovers new requirements or completes tasks. See protocol docs: Agent Plan Type: Object Properties:

object | null

PlanEntry[]

required

The list of tasks to be accomplished.When updating a plan, the agent must send a complete list of all entries with their current status. The client replaces the entire plan with each update.

PlanCapabilities

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Capabilities for receiving plan_update and plan_removed session updates. Type: Object Properties:

object | null

PlanEntry

A single entry in the execution plan. Represents a task or goal that the assistant intends to accomplish as part of fulfilling the user’s request. See protocol docs: Plan Entries Type: Object Properties:

object | null

string

required

Human-readable description of what this task aims to accomplish.

PlanEntryPriority

required

The relative importance of this task. Used to indicate which tasks are most critical to the overall goal.

PlanEntryStatus

required

Current execution status of this task.

PlanEntryPriority

Priority levels for plan entries. Used to indicate the relative importance or urgency of different tasks in the execution plan. See protocol docs: Plan Entries Type: Union

string

High priority task - critical to the overall goal.

string

Medium priority task - important but not critical.

string

Low priority task - nice to have but not essential.

PlanEntryStatus

Status of a plan entry in the execution flow. Tracks the lifecycle of each task from planning through completion. See protocol docs: Plan Entries Type: Union

string

The task has not started yet.

string

The task is currently being worked on.

string

The task has been successfully completed.

PlanFile

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. A plan represented by a file URI. Type: Object Properties:

object | null

PlanId

required

The plan ID to update.

string

required

The URI of the file containing the plan.

PlanId

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Unique identifier for a plan within a session. Type: string

PlanItems

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. A plan represented as structured entries. Type: Object Properties:

object | null

PlanEntry[]

required

The list of tasks to be accomplished.When updating an item-based plan, the agent must send a complete list of all entries with their current status. The client replaces that plan with each update.

PlanId

required

The plan ID to update.

PlanMarkdown

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. A plan represented as raw markdown content. Type: Object Properties:

object | null

string

required

Markdown content for the plan.

PlanId

required

The plan ID to update.

PlanRemoved

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Removal notice for a plan identified by ID. Type: Object Properties:

object | null

PlanId

required

The plan ID to remove.

PlanUpdate

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. A content update for a plan identified by ID. Type: Object Properties:

object | null

PlanUpdateContent

required

The updated plan content.

PlanUpdateContent

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Updated content for a plan. Type: Union

object

Structured plan entries.

Show Properties

object | null

PlanEntry[]

required

The list of tasks to be accomplished.When updating an item-based plan, the agent must send a complete list of all entries with their current status. The client replaces that plan with each update.

PlanId

required

The plan ID to update.

string

required

The discriminator value. Must be "items".

object

A URI pointing to a file containing the plan.

Show Properties

object | null

PlanId

required

The plan ID to update.

string

required

The discriminator value. Must be "file".

string

required

The URI of the file containing the plan.

object

Raw markdown content for the plan.

Show Properties

object | null

string

required

Markdown content for the plan.

PlanId

required

The plan ID to update.

string

required

The discriminator value. Must be "markdown".

Position

A zero-based position in a text document. The meaning of character depends on the negotiated position encoding. Type: Object Properties:

object | null

uint32

required

Zero-based character offset (encoding-dependent).

Minimum: 0

uint32

required

Zero-based line number.

Minimum: 0

PositionEncodingKind

The encoding used for character offsets in positions. Follows the same conventions as LSP 3.17. The default is UTF-16. Type: Union

string

Character offsets count UTF-16 code units. This is the default.

string

Character offsets count Unicode code points.

string

Character offsets count UTF-8 code units (bytes).

PromptCapabilities

Prompt capabilities supported by the agent in session/prompt requests. Baseline agent functionality requires support for ContentBlock::Text and ContentBlock::ResourceLink in prompt requests. Other variants must be explicitly opted in to. Capabilities for different types of content in prompt requests. Indicates which content types beyond the baseline (text and resource links) the agent can process. See protocol docs: Prompt Capabilities Type: Object Properties:

object | null

boolean

Agent supports ContentBlock::Audio.

Default: false

boolean

Agent supports embedded context in session/prompt requests.When enabled, the Client is allowed to include ContentBlock::Resource in prompt requests for pieces of context that are referenced in the message.

Default: false

boolean

Agent supports ContentBlock::Image.

Default: false

ProtocolVersion

Protocol version identifier. This version is only bumped for breaking changes. Non-breaking changes should be introduced via capabilities. Type: integer (uint16)

Constraint	Value
Minimum	`0`
Maximum	`65535`

ProviderCurrentConfig

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Current effective non-secret routing configuration for a provider. Type: Object Properties:

object | null

LlmProtocol

required

Protocol currently used by this provider.

string

required

Base URL currently used by this provider.

ProviderId

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Unique identifier for a configurable LLM provider. Type: string

ProviderInfo

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Information about a configurable LLM provider. Type: Object Properties:

object | null

ProviderCurrentConfig | null

Current effective non-secret routing config. Null or omitted means provider is disabled.

ProviderId

required

Provider identifier, for example “main” or “openai”.

boolean

required

Whether this provider is mandatory and cannot be disabled via providers/disable. If true, clients must not call providers/disable for this provider ID.

LlmProtocol[]

required

Supported protocol types for this provider.

ProvidersCapabilities

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Provider configuration capabilities supported by the agent. Supplying \{\} means the agent supports provider configuration methods. Type: Object Properties:

object | null

Range

A range in a text document, expressed as start and end positions. Type: Object Properties:

object | null

Position

required

The end position (exclusive).

Position

required

The start position (inclusive).

RequestId

JSON RPC Request Id An identifier established by the Client that MUST contain a String, Number, or NULL value if included. If it is not included it is assumed to be a notification. The value SHOULD normally not be Null [1] and Numbers SHOULD NOT contain fractional parts [2] The Server MUST reply with the same value in the Response object if included. This member is used to correlate the context between the two objects. [1] The use of Null as a value for the id member in a Request object is discouraged, because this specification uses a value of Null for Responses with an unknown id. Also, because JSON-RPC 1.0 uses an id value of Null for Notifications this could cause confusion in handling. [2] Fractional parts may be problematic, since many decimal fractions cannot be represented exactly as binary fractions. Type: Union

null

The JSON-RPC null request id.

int64

A numeric JSON-RPC request id.

string

A string JSON-RPC request id.

RequestPermissionOutcome

The outcome of a permission request. Type: Union

object

The prompt turn was cancelled before the user responded.When a client sends a session/cancel notification to cancel an ongoing prompt turn, it MUST respond to all pending session/request_permission requests with this Cancelled outcome.See protocol docs: Cancellation

Show Properties

string

required

The discriminator value. Must be "cancelled".

object

The user selected one of the provided options.

Show Properties

object | null

PermissionOptionId

required

The ID of the option the user selected.

string

required

The discriminator value. Must be "selected".

ResourceLink

A resource that the server is capable of reading, included in a prompt or tool call result. Type: Object Properties:

object | null

Annotations | null

Optional annotations that help clients decide how to display or route this content.

string | null

Optional human-readable details shown with this protocol object.

string | null

MIME type describing the encoded media payload.

string

required

Human-readable name shown for this protocol object.

integer | null

Optional size of the linked resource in bytes, if known.

string | null

Optional display title for end-user UI.

string

required

URI associated with this resource or media payload.

Role

The sender or recipient of messages and data in a conversation. Type: Union

string

The assistant side of a conversation.

string

The user side of a conversation.

SelectedPermissionOutcome

The user selected one of the provided options. Type: Object Properties:

object | null

PermissionOptionId

required

The ID of the option the user selected.

SessionAdditionalDirectoriesCapabilities

Capabilities for additional session directories support. Supplying \{\} means the agent supports the additionalDirectories field on supported session lifecycle requests. Agents that also support session/list may return SessionInfo.additionalDirectories to report the complete ordered additional-root list associated with a listed session. Type: Object Properties:

object | null

SessionCapabilities

Session capabilities supported by the agent. As a baseline, all Agents MUST support session/new, session/prompt, session/cancel, and session/update. Optionally, they MAY support other session methods and notifications by specifying additional capabilities. Note: session/load is still handled by the top-level load_session capability. This will be unified in future versions of the protocol. See protocol docs: Session Capabilities Type: Object Properties:

object | null

SessionAdditionalDirectoriesCapabilities | null

Whether the agent supports additionalDirectories on supported session lifecycle requests.Optional. Omitted or null both mean the agent does not advertise support. Supplying \{\} means the agent supports additionalDirectories on supported session lifecycle requests.Agents that also support session/list may return SessionInfo.additionalDirectories to report the complete ordered additional-root list associated with a listed session.

SessionCloseCapabilities | null

Whether the agent supports session/close.Optional. Omitted or null both mean the agent does not advertise support. Supplying \{\} means the agent supports closing sessions.

SessionDeleteCapabilities | null

Whether the agent supports session/delete.Optional. Omitted or null both mean the agent does not advertise support. Supplying \{\} means the agent supports deleting sessions from session/list.

SessionForkCapabilities | null

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.Whether the agent supports session/fork.Optional. Omitted or null both mean the agent does not advertise support. Supplying \{\} means the agent supports forking sessions.

SessionListCapabilities | null

Whether the agent supports session/list.Optional. Omitted or null both mean the agent does not advertise support. Supplying \{\} means the agent supports listing sessions.

SessionResumeCapabilities | null

Whether the agent supports session/resume.Optional. Omitted or null both mean the agent does not advertise support. Supplying \{\} means the agent supports resuming sessions.

SessionCloseCapabilities

Capabilities for the session/close method. Supplying \{\} means the agent supports closing sessions. Type: Object Properties:

object | null

SessionConfigBoolean

A boolean on/off toggle session configuration option payload. Type: Object Properties:

boolean

required

The current value of the boolean option.

SessionConfigGroupId

Unique identifier for a session configuration option value group. Type: string

SessionConfigId

Unique identifier for a session configuration option. Type: string

SessionConfigOption

A session configuration option selector and its current state. Type: Union Shared properties:

object | null

SessionConfigOptionCategory | null

Optional semantic category for this option (UX only).

string | null

Optional description for the Client to display to the user.

SessionConfigId

required

Unique identifier for the configuration option.

string

required

Human-readable label for the option.

Variants:

object

Single-value selector (dropdown).

Show Properties

SessionConfigValueId

required

The currently selected value.

SessionConfigSelectOptions

required

The set of selectable options.

string

required

The discriminator value. Must be "select".

object

Boolean on/off toggle.

Show Properties

boolean

required

The current value of the boolean option.

string

required

The discriminator value. Must be "boolean".

SessionConfigOptionCategory

Semantic category for a session configuration option. This is intended to help Clients distinguish broadly common selectors (e.g. model selector vs session mode selector vs thought/reasoning level) for UX purposes (keyboard shortcuts, icons, placement). It MUST NOT be required for correctness. Clients MUST handle missing or unknown categories gracefully. Category names beginning with _ are free for custom use, like other ACP extension methods. Category names that do not begin with _ are reserved for the ACP spec. Type: Union

string

Session mode selector.

string

Model selector.

string

Model-related configuration parameter.

string

Thought/reasoning level selector.

string

Unknown / uncategorized selector.

SessionConfigOptionsCapabilities

Session configuration option capabilities supported by the client. Type: Object Properties:

object | null

BooleanConfigOptionCapabilities | null

Whether the client supports boolean session configuration options.Optional. Omitted or null both mean the client does not advertise support. Supplying \{\} means agents may include type: "boolean" entries in configOptions, and the client may send session/set_config_option requests with type: "boolean" and a boolean value.

SessionConfigSelect

A single-value selector (dropdown) session configuration option payload. Type: Object Properties:

SessionConfigValueId

required

The currently selected value.

SessionConfigSelectOptions

required

The set of selectable options.

SessionConfigSelectGroup

A group of possible values for a session configuration option. Type: Object Properties:

object | null

SessionConfigGroupId

required

Unique identifier for this group.

string

required

Human-readable label for this group.

SessionConfigSelectOption[]

required

The set of option values in this group.

SessionConfigSelectOption

A possible value for a session configuration option. Type: Object Properties:

object | null

string | null

Optional description for this option value.

string

required

Human-readable label for this option value.

SessionConfigValueId

required

Unique identifier for this option value.

SessionConfigSelectOptions

Possible values for a session configuration option. Type: Union

array

A flat list of options with no grouping.

array

A list of options grouped under headers.

SessionConfigValueId

Unique identifier for a session configuration option value. Type: string

SessionDeleteCapabilities

Capabilities for the session/delete method. Supplying \{\} means the agent supports deleting sessions from session/list. Type: Object Properties:

object | null

SessionForkCapabilities

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Capabilities for the session/fork method. Supplying \{\} means the agent supports forking sessions. Type: Object Properties:

object | null

SessionId

A unique identifier for a conversation session between a client and agent. Sessions maintain their own context, conversation history, and state, allowing multiple independent interactions with the same agent. See protocol docs: Session ID Type: string

SessionInfo

Information about a session returned by session/list Type: Object Properties:

object | null

"string"[]

Additional workspace roots reported for this session. Each path must be absolute.When present, this is the complete ordered additional-root list reported by the Agent. Omitted and empty values are equivalent: the response reports no additional roots.

string

required

The working directory for this session. Must be an absolute path.

SessionId

required

Unique identifier for the session

string | null

Human-readable title for the session

string | null

ISO 8601 timestamp of last activity

SessionInfoUpdate

Update to session metadata. All fields are optional to support partial updates. Agents send this notification to update session information like title or custom metadata. This allows clients to display dynamic session names and track session state changes. Type: Object Properties:

object | null

string | null

Human-readable title for the session. Set to null to clear.

string | null

ISO 8601 timestamp of last activity. Set to null to clear.

SessionListCapabilities

Capabilities for the session/list method. Supplying \{\} means the agent supports listing sessions. Type: Object Properties:

object | null

SessionMode

A mode the agent can operate in. See protocol docs: Session Modes Type: Object Properties:

object | null

string | null

Optional human-readable details shown with this protocol object.

SessionModeId

required

Stable identifier used to refer to this protocol object in later messages.

string

required

Human-readable name shown for this protocol object.

SessionModeId

Unique identifier for a Session Mode. Type: string

SessionModeState

The set of modes and the one currently active. Type: Object Properties:

object | null

SessionMode[]

required

The set of modes that the Agent can operate in

SessionModeId

required

The current mode the Agent is in.

SessionResumeCapabilities

Capabilities for the session/resume method. Supplying \{\} means the agent supports resuming sessions. Type: Object Properties:

object | null

SessionUpdate

Different types of updates that can be sent during session processing. These updates provide real-time feedback about the agent’s progress. See protocol docs: Agent Reports Output Type: Union

object

A chunk of the user’s message being streamed.

Show Properties

object | null

ContentBlock

required

A single item of content

MessageId | null

A unique identifier for the message this chunk belongs to.All chunks belonging to the same message share the same messageId. A change in messageId indicates a new message has started.

string

required

The discriminator value. Must be "user_message_chunk".

object

A chunk of the agent’s response being streamed.

Show Properties

object | null

ContentBlock

required

A single item of content

MessageId | null

A unique identifier for the message this chunk belongs to.All chunks belonging to the same message share the same messageId. A change in messageId indicates a new message has started.

string

required

The discriminator value. Must be "agent_message_chunk".

object

A chunk of the agent’s internal reasoning being streamed.

Show Properties

object | null

ContentBlock

required

A single item of content

MessageId | null

A unique identifier for the message this chunk belongs to.All chunks belonging to the same message share the same messageId. A change in messageId indicates a new message has started.

string

required

The discriminator value. Must be "agent_thought_chunk".

object

Notification that a new tool call has been initiated.

Show Properties

object | null

ToolCallContent[]

Content produced by the tool call.

ToolKind

The category of tool being invoked. Helps clients choose appropriate icons and UI treatment.

ToolCallLocation[]

File locations affected by this tool call. Enables “follow-along” features in clients.

string | null

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.Programmatic name of the tool being invoked.This field is optional. Omitting it or sending null both mean that no tool name is available.

object

Raw input parameters sent to the tool.

object

Raw output returned by the tool.

string

required

The discriminator value. Must be "tool_call".

ToolCallStatus

Current execution status of the tool call.

string

required

Human-readable title describing what the tool is doing.

ToolCallId

required

Unique identifier for this tool call within the session.

object

Update on the status or results of a tool call.

Show Properties

object | null

ToolCallContent[] | null

Replace the content collection.

ToolKind | null

Update the tool kind.

ToolCallLocation[] | null

Replace the locations collection.

string | null

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.Update the programmatic name of the tool being invoked.This field is optional. Omitting it or sending null both mean that the existing name is left unchanged.

object

Update the raw input.

object

Update the raw output.

string

required

The discriminator value. Must be "tool_call_update".

ToolCallStatus | null

Update the execution status.

string | null

Update the human-readable title.

ToolCallId

required

The ID of the tool call being updated.

object

The agent’s execution plan for complex tasks. See protocol docs: Agent Plan

Show Properties

object | null

PlanEntry[]

required

The list of tasks to be accomplished.When updating a plan, the agent must send a complete list of all entries with their current status. The client replaces the entire plan with each update.

string

required

The discriminator value. Must be "plan".

object

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.A content update for a plan identified by ID.

Show Properties

object | null

PlanUpdateContent

required

The updated plan content.

string

required

The discriminator value. Must be "plan_update".

object

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.Removal notice for a plan identified by ID.

Show Properties

object | null

PlanId

required

The plan ID to remove.

string

required

The discriminator value. Must be "plan_removed".

object

Available commands are ready or have changed

Show Properties

object | null

AvailableCommand[]

required

Commands the agent can execute

string

required

The discriminator value. Must be "available_commands_update".

object

The current mode of the session has changedSee protocol docs: Session Modes

Show Properties

object | null

SessionModeId

required

The ID of the current mode

string

required

The discriminator value. Must be "current_mode_update".

object

Session configuration options have been updated.

Show Properties

object | null

SessionConfigOption[]

required

The full set of configuration options and their current values.

string

required

The discriminator value. Must be "config_option_update".

object

Session metadata has been updated (title, timestamps, custom metadata)

Show Properties

object | null

string

required

The discriminator value. Must be "session_info_update".

string | null

Human-readable title for the session. Set to null to clear.

string | null

ISO 8601 timestamp of last activity. Set to null to clear.

object

Context window and cost update for the session.

Show Properties

object | null

Cost | null

Cumulative session cost (optional).

string

required

The discriminator value. Must be "usage_update".

uint64

required

Total context window size in tokens.

Minimum: 0

uint64

required

Tokens currently in context.

Minimum: 0

object

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.Advisory information for the user that is not part of session history.No Client capability is required. Clients that do not understand or present notices may ignore them.

Show Properties

object | null

Metadata scoped to this notice.Omitted and null are equivalent and mean no metadata was supplied.

string | null

Optional plain-text detail or guidance.Omitted and null are equivalent and mean no description was supplied.

string

required

The discriminator value. Must be "notice".

NoticeSeverity

required

Presentation severity hint.

string

required

Required non-empty plain-text title that can stand alone.

Min length: 1

object

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.A context compaction has been created or updated.Agents MUST only send this update when the Client advertised ClientSessionCapabilities::compaction.

Show Properties

object | null

Extensible metadata patch for this compaction.

CompactionId

required

The Agent-owned ID of this compaction, unique within the session.

string | null

Human-readable description of why the compaction failed.

string

required

The discriminator value. Must be "compaction_update".

CompactionStatus

required

Current lifecycle status.

ContentBlock[] | null

Complete replacement user-displayable summary retained by the compaction.

object

UNSTABLEThis capability is not part of the spec yet, and may be removed or changed at any point.A content block appended to a context compaction’s retained summary.Agents MUST only send this update when the Client advertised ClientSessionCapabilities::compaction.

Show Properties

object | null

Metadata scoped to this chunk. Omission and null both mean absent.

CompactionId

required

ID of the compaction whose summary receives this content.

ContentBlock

required

One content block to append.

string

required

The discriminator value. Must be "compaction_summary_chunk".

StopReason

Reasons why an agent stops processing a prompt turn. See protocol docs: Stop Reasons Type: Union

string

The turn ended successfully.

string

The turn ended because the agent reached the maximum number of tokens.

string

The turn ended because the agent reached the maximum number of allowed agent requests between user turns.

string

The turn ended because the agent refused to continue. The user prompt and everything that comes after it won’t be included in the next prompt, so this should be reflected in the UI.

string

The turn was cancelled by the client via session/cancel.This stop reason MUST be returned when the client sends a session/cancel notification, even if the cancellation causes exceptions in underlying operations. Agents should catch these exceptions and return this semantically meaningful response to confirm successful cancellation.

StringFormat

String format types for string properties in elicitation schemas. Type: Union

string

Email address format.

string

URI format.

string

Date format (YYYY-MM-DD).

string

Date-time format (ISO 8601).

StringMultiSelectItems

String item schema for multi-select enum properties. Type: Object Properties:

object | null

"string"[]

required

Allowed enum values.

StringPropertySchema

Schema for string properties in an elicitation form. When enum or oneOf is set, this represents a single-select enum with "type": "string". Type: Object Properties:

object | null

string | null

Default value.Optional. Omitted and null are equivalent and mean no default value is provided.

string | null

Human-readable description.Optional. Omitted and null are equivalent and mean no description is provided.

"string"[] | null

Enum values for untitled single-select enums. Optional. Omitted and null are equivalent and mean no untitled single-select choices are declared by enum.

StringFormat | null

String format.Optional. Omitted and null are equivalent and mean there is no format constraint.

integer | null

Maximum string length.Optional. Omitted and null are equivalent and mean there is no maximum length constraint.

Minimum: 0

integer | null

Minimum string length.Optional. Omitted and null are equivalent and mean there is no minimum length constraint.

Minimum: 0

EnumOption[] | null

Titled enum options for titled single-select enums. Optional. Omitted and null are equivalent and mean no titled single-select choices are declared by oneOf.

string | null

Pattern the string must match.Optional. Omitted and null are equivalent and mean there is no pattern constraint.

string | null

Optional title for the property.Optional. Omitted and null are equivalent and mean no title is provided.

Terminal

Embed a terminal created with terminal/create by its id. The terminal must be added before calling terminal/release. See protocol docs: Terminal Type: Object Properties:

object | null

TerminalId

required

Identifier of the terminal instance to embed in the content stream.

TerminalExitStatus

Exit status of a terminal command. Type: Object Properties:

object | null

integer | null

The process exit code (may be null if terminated by signal).

Minimum: 0

string | null

The signal that terminated the process (may be null if exited normally).

TerminalId

Typed identifier used for terminal values on the wire. Type: string

TextContent

Text provided to or from an LLM. Type: Object Properties:

object | null

Annotations | null

Optional annotations that help clients decide how to display or route this content.

string

required

Text payload carried by this content block.

TextDocumentContentChangeEvent

A content change event for a document. When range is None, text is the full content of the document. When range is Some, text replaces the given range. Type: Object Properties:

object | null

Range | null

The range of the document that changed. If None, the entire content is replaced.

string

required

The new text for the range, or the full document content if range is None.

TextDocumentSyncKind

How the agent wants document changes delivered. Type: Union

string

Client sends the entire file content on each change.

string

Client sends only the changed ranges.

TextResourceContents

Text-based resource contents. Type: Object Properties:

object | null

string | null

MIME type describing the encoded media payload.

string

required

Text payload carried by this content block.

string

required

URI associated with this resource or media payload.

TitledMultiSelectItems

Items definition for titled multi-select enum properties. Type: Object Properties:

object | null

EnumOption[]

required

Titled enum options.

ToolCall

Represents a tool call that the language model has requested. Tool calls are actions that the agent executes on behalf of the language model, such as reading files, executing code, or fetching data from external sources. See protocol docs: Tool Calls Type: Object Properties:

object | null

ToolCallContent[]

Content produced by the tool call.

ToolKind

The category of tool being invoked. Helps clients choose appropriate icons and UI treatment.

ToolCallLocation[]

File locations affected by this tool call. Enables “follow-along” features in clients.

string | null

object

Raw input parameters sent to the tool.

object

Raw output returned by the tool.

ToolCallStatus

Current execution status of the tool call.

string

required

Human-readable title describing what the tool is doing.

ToolCallId

required

Unique identifier for this tool call within the session.

ToolCallContent

Content produced by a tool call. Tool calls can produce different types of content including standard content blocks (text, images) or file diffs. See protocol docs: Content Type: Union

object

Standard content block (text, images, resources).

Show Properties

object | null

ContentBlock

required

The actual content block.

string

required

The discriminator value. Must be "content".

object

File modification shown as a diff.

Show Properties

object | null

string

required

The new content after modification.

string | null

The original content (None for new files).

string

required

The absolute file path being modified.

string

required

The discriminator value. Must be "diff".

object

Embed a terminal created with terminal/create by its id.The terminal must be added before calling terminal/release.See protocol docs: Terminal

Show Properties

object | null

TerminalId

required

Identifier of the terminal instance to embed in the content stream.

string

required

The discriminator value. Must be "terminal".

ToolCallId

Unique identifier for a tool call within a session. Type: string

ToolCallLocation

A file location being accessed or modified by a tool. Enables clients to implement “follow-along” features that track which files the agent is working with in real-time. See protocol docs: Following the Agent Type: Object Properties:

object | null

integer | null

Optional line number within the file.

Minimum: 0

string

required

The absolute file path being accessed or modified.

ToolCallStatus

Execution status of a tool call. Tool calls progress through different statuses during their lifecycle. See protocol docs: Status Type: Union

string

The tool call hasn’t started running yet because the input is either streaming or we’re awaiting approval.

string

The tool call is currently running.

string

The tool call completed successfully.

string

The tool call failed with an error.

ToolCallUpdate

An update to an existing tool call. Used to report progress and results as tools execute. All fields except the tool call ID are optional - only changed fields need to be included. See protocol docs: Updating Type: Object Properties:

object | null

ToolCallContent[] | null

Replace the content collection.

ToolKind | null

Update the tool kind.

ToolCallLocation[] | null

Replace the locations collection.

string | null

object

Update the raw input.

object

Update the raw output.

ToolCallStatus | null

Update the execution status.

string | null

Update the human-readable title.

ToolCallId

required

The ID of the tool call being updated.

ToolKind

Categories of tools that can be invoked. Tool kinds help clients choose appropriate icons and optimize how they display tool execution progress. See protocol docs: Creating Type: Union

string

Reading files or data.

string

Modifying files or content.

string

Removing files or data.

string

Moving or renaming files.

string

Searching for information.

string

Running commands or code.

string

Internal reasoning or planning.

string

Retrieving external data.

string

Switching the current session mode.

string

Other tool types (default).

UnstructuredCommandInput

All text that was typed after the command name is provided as input. Type: Object Properties:

object | null

string

required

A hint to display when the input hasn’t been provided yet

Usage

UNSTABLE This capability is not part of the spec yet, and may be removed or changed at any point. Token usage information for a prompt turn. Type: Object Properties:

object | null

integer | null

Total cache read tokens.

Minimum: 0

integer | null

Total cache write tokens.

Minimum: 0

uint64

required

Total input tokens across all turns.

Minimum: 0

uint64

required

Total output tokens across all turns.

Minimum: 0

integer | null

Total thought/reasoning tokens

Minimum: 0

uint64

required

Sum of all token types across session.

Minimum: 0

UsageUpdate

Context window and cost update for a session. Type: Object Properties:

object | null

Cost | null

Cumulative session cost (optional).

uint64

required

Total context window size in tokens.

Minimum: 0

uint64

required

Tokens currently in context.

Minimum: 0

WorkspaceFolder

A workspace folder. Type: Object Properties:

object | null

string

required

The display name of the folder.

string

required

The URI of the folder.

​Agent

​authenticate

​AuthenticateRequest

​AuthenticateResponse

​document/didChange

​DidChangeDocumentNotification

​document/didClose

​DidCloseDocumentNotification

​document/didFocus

​DidFocusDocumentNotification

​document/didOpen

​DidOpenDocumentNotification

​document/didSave

​DidSaveDocumentNotification

​initialize

​InitializeRequest

​InitializeResponse

​logout

​LogoutRequest

​LogoutResponse

​mcp/message

​MessageMcpNotification

​MessageMcpRequest

​MessageMcpResponse

​nes/accept

​AcceptNesNotification

​nes/close

​CloseNesRequest

​CloseNesResponse

​nes/reject

​RejectNesNotification

​nes/start

​StartNesRequest

​StartNesResponse

​nes/suggest

​SuggestNesRequest

​SuggestNesResponse

​providers/disable

​DisableProviderRequest

​DisableProviderResponse

​providers/list

​ListProvidersRequest

​ListProvidersResponse

​providers/set

​SetProviderRequest

​SetProviderResponse

​session/cancel

​CancelNotification

​session/close

​CloseSessionRequest

​CloseSessionResponse

​session/delete

​DeleteSessionRequest

​DeleteSessionResponse

​session/fork

​ForkSessionRequest

​ForkSessionResponse

​session/list

​ListSessionsRequest

​ListSessionsResponse

​session/load

​LoadSessionRequest

​LoadSessionResponse

​session/new

​NewSessionRequest

​NewSessionResponse

​session/prompt

​PromptRequest

​PromptResponse

​session/resume

​ResumeSessionRequest

​ResumeSessionResponse

​session/set_config_option

​SetSessionConfigOptionRequest

​SetSessionConfigOptionResponse

​session/set_mode

​SetSessionModeRequest

​SetSessionModeResponse

​Client

​elicitation/complete

Agent

authenticate

AuthenticateRequest

AuthenticateResponse

document/didChange

DidChangeDocumentNotification

document/didClose

DidCloseDocumentNotification

document/didFocus

DidFocusDocumentNotification

document/didOpen

DidOpenDocumentNotification

document/didSave

DidSaveDocumentNotification

initialize

InitializeRequest

InitializeResponse

logout

LogoutRequest

LogoutResponse

mcp/message

MessageMcpNotification

MessageMcpRequest

MessageMcpResponse

nes/accept

AcceptNesNotification

nes/close

CloseNesRequest

CloseNesResponse

nes/reject

RejectNesNotification

nes/start

StartNesRequest

StartNesResponse

nes/suggest

SuggestNesRequest

SuggestNesResponse

providers/disable

DisableProviderRequest

DisableProviderResponse

providers/list

ListProvidersRequest

ListProvidersResponse

providers/set

SetProviderRequest

SetProviderResponse

session/cancel

CancelNotification

session/close

CloseSessionRequest

CloseSessionResponse

session/delete

DeleteSessionRequest

DeleteSessionResponse

session/fork

ForkSessionRequest

ForkSessionResponse

session/list

ListSessionsRequest

ListSessionsResponse

session/load

LoadSessionRequest

LoadSessionResponse

session/new

NewSessionRequest

NewSessionResponse

session/prompt

PromptRequest

PromptResponse

session/resume

ResumeSessionRequest

ResumeSessionResponse

session/set_config_option

SetSessionConfigOptionRequest

SetSessionConfigOptionResponse

session/set_mode

SetSessionModeRequest

SetSessionModeResponse

Client

elicitation/complete