Revoke the tool mid-turn

A customer's agent is halfway through a turn when you need its Jira integration gone: the connector is misbehaving, or the contract ended at noon.

You disable the MCP server: POST /api/v1/agent/mcp/servers/enable with the flag off, or one keypress in the Agents tab. The cutoff is immediate and applies to the session that's already open. No new call to that server is admitted from that point, mid-turn. A call already sent is allowed to return its result, since the server already acted; nothing after it gets through. The servers you didn't touch are never restarted by the change.

You don't wait for the turn to end. You don't kill the session and lose its context. The tool is gone, and the agent keeps going with the tools it has left.