How to expose mcp_session_id to user ? #942

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1. sequoiar

   added

   questionFurther information is requestedFurther information is requested

   on Jun 12, 2025
2. hesreallyhim commented on Jun 12, 2025

   

   hesreallyhim

   on Jun 12, 2025

   Contributor

   More actions

   Check out the spec, I think it belongs in the header:
   https://modelcontextprotocol.io/specification/2025-03-26/basic/transports#session-management

   A server using the Streamable HTTP transport MAY assign a session ID at initialization time, by including it in an Mcp-Session-Id header on the HTTP response containing the InitializeResult.

   I'm not familiar enough to know how the sdk exposes the response headers, sorry.
3. zhenjunMa commented on Jun 15, 2025

   

   zhenjunMa

   on Jun 15, 2025

   Last edited by zhenjunMa

   More actions

   You can retrieve the raw request from the request context and then access any data you want.

   app = Server("mcp-streamable-http-demo")
   
   @app.call_tool()
   def add(a: int, b: int) -> int:
       from starlette.requests import Request
       session_id = cast(Request, app.request_context.request).headers.get("mcp-session-id")
       print(session_id)
       return a + b

   👍React with 👍3Reacted by tom zhou, Greg Sadetsky and Felix Weinberger
4. Sunrisea commented on Jun 17, 2025

   

   Sunrisea

   on Jun 17, 2025

   More actions

   You can retrieve the raw request from the request context and then access any data you want.

   app = Server("mcp-streamable-http-demo")

   @app.call_tool()
   def add(a: int, b: int) -> int:
   from starlette.requests import Request
   session_id = cast(Request, app.request_context.request).headers.get("mcp-session-id")
   print(session_id)
   return a + b

   I tried it, but I cant get session_id in this way
5. felixweinberger

   added

   enhancementRequest for a new feature that's not currently supportedRequest for a new feature that's not currently supported

   ready for workEnough information for someone to start working onEnough information for someone to start working on

   P1Significant bug affecting many users, highly requested featureSignificant bug affecting many users, highly requested feature

   and removed

   questionFurther information is requestedFurther information is requested

   on Oct 6, 2025
6. cbcoutinho

   added a commit that references this issue on Nov 10, 2025

   feat: propagate session_id from transport to tool context

   ...

   3ca0718
7. maxisbey commented on Feb 19, 2026

   

   maxisbey

   on Feb 19, 2026

   Contributor

   More actions

   Now tracked in #2098.
8. maxisbey

   closed this as completedon Feb 19, 2026