> ## Documentation Index
> Fetch the complete documentation index at: https://agentclientprotocol.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Client-provided system prompts are stabilized

> Clients can send system-level instructions on session setup in the stable ACP protocol surfaces.

**Published:** November 6, 2026

The [Client-Provided System Prompt RFD](https://agentclientprotocol.com/rfds/client-system-prompt.md) has moved to
Completed, stabilizing the `systemPrompt` field on session setup requests and
the `systemPrompt` session capability.

For protocol details, see [v1 Session Setup](https://agentclientprotocol.com/protocol/v1/session-setup.md#system-prompt)
and [v2 Session Setup](https://agentclientprotocol.com/protocol/v2/session-setup.md#system-prompt).


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