Send a Workflow MCP message

POST 
/api/workflows/:workflowName/mcp

Standard Streamable HTTP MCP JSON-RPC endpoint. It accepts only an account API Key or administrator Key in Authorization: Bearer; browser cookie sessions are rejected. Omit Mcp-Session-Id for initialize. The initialization response returns that header, and every later request must use the same session ID, Bearer credential, project, and target. Normal JSON-RPC request responses are delivered through SSE. Messages containing only notifications or responses return 202.

Request

Responses

200

SSE stream carrying a JSON-RPC response; initialize also returns the session ID.

Response Headers

Mcp-Session-Id

Session ID created during initialize; send it unchanged on later requests.

202

Notification or client response accepted with no response body.

400

Invalid target, session header, or JSON-RPC message.

401

Missing Bearer credentials or not a valid account API Key / administrator Key.

Response Headers

WWW-Authenticate
Example: Bearer

403

Missing project run access, or the session belongs to another credential, project, or target.

404

MCP session does not exist or has expired.

406

Accept does not include both application/json and text/event-stream.

409

Session target or draft revision changed; reconnect is required.

415

Content-Type is not application/json.