Support for http request injection propagation to tools (#816)

src/mcp/shared/context.py

@@ -8,11 +8,13 @@ from mcp.types import RequestId, RequestParams
 
 SessionT = TypeVar("SessionT", bound=BaseSession[Any, Any, Any, Any, Any])
 LifespanContextT = TypeVar("LifespanContextT")
+RequestT = TypeVar("RequestT", default=Any)
 
 
 @dataclass
-class RequestContext(Generic[SessionT, LifespanContextT]):
+class RequestContext(Generic[SessionT, LifespanContextT, RequestT]):
     request_id: RequestId
     meta: RequestParams.Meta | None
     session: SessionT
     lifespan_context: LifespanContextT
+    request: RequestT | None = None

src/mcp/shared/message.py

@@ -30,6 +30,8 @@ class ServerMessageMetadata:
     """Metadata specific to server messages."""
 
     related_request_id: RequestId | None = None
+    # Request-specific context (e.g., headers, auth info)
+    request_context: object | None = None
 
 
 MessageMetadata = ClientMessageMetadata | ServerMessageMetadata | None

src/mcp/shared/session.py

@@ -81,10 +81,12 @@ class RequestResponder(Generic[ReceiveRequestT, SendResultT]):
             ReceiveNotificationT
         ]""",
         on_complete: Callable[["RequestResponder[ReceiveRequestT, SendResultT]"], Any],
+        message_metadata: MessageMetadata = None,
     ) -> None:
         self.request_id = request_id
         self.request_meta = request_meta
         self.request = request
+        self.message_metadata = message_metadata
         self._session = session
         self._completed = False
         self._cancel_scope = anyio.CancelScope()
@@ -365,6 +367,7 @@ class BaseSession(
                         request=validated_request,
                         session=self,
                         on_complete=lambda r: self._in_flight.pop(r.request_id, None),
+                        message_metadata=message.metadata,
                     )
 
                     self._in_flight[responder.request_id] = responder