Claude Code: disable an MCP server mid-session, Sume jobs persist
Switching off an MCP server in Claude Code SDK sessions removes its tools for new calls. Sume jobs already submitted keep running until you read or cancel them.
Disabling an MCP server stops your session from making new calls to it; it does not undo work already submitted. Claude Code 2.1.285 fixed a bug where switching off an MCP server added mid-session, in SDK and -p sessions, left its tools available. For Sume, any video or image job already created keeps its own id and state, so read it with jobs_status or cancel it with jobs_cancel.
Changelog entry read 2026-10-01; Sume behavior from Jobs and results and MCP tools and gates.
What did Claude Code 2.1.285 fix?
The 2026-09-29 changelog says: "Fixed switching off an MCP server added mid-session in SDK and -p sessions leaving its tools available". Before the fix, a server you had turned off could still have its tools callable. If you drive Claude Code from the SDK or print mode, update before relying on a toggle as a spend control.
What stops, and what keeps going?
| Thing | After the server is off |
|---|---|
New paid calls such as generate_image | Not available from this session |
| A job already submitted | Keeps its state on Sume; the docs say do not resubmit the paid request |
| Reading it later | jobs_status / jobs_result after you reconnect, or the job API |
| Cancelling it | jobs_cancel, a write tool needing idempotency_key |
Can I cancel after disconnecting?
Only through a session that can call write tools. An OAuth mcp:read token cannot: write tools such as jobs_cancel return insufficient_scope. Use mcp:read plus mcp:write, an API key, or the POST /v1/jobs/{id}/cancel endpoint. Cancellation succeeds only before generation starts; after that the API returns 409 job_generation_already_started and the job runs to completion.
How do I keep a toggle from orphaning jobs?
Record each job_id when the create tool returns, and wait for or cancel those jobs before you switch the server off. For subagent setups, see Claude Code subagent MCP server.
Sources
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