Added support for raw request injection in RequestContext.

src/mcp/client/session.py

@@ -17,14 +17,14 @@
 class SamplingFnT(Protocol):
     async def __call__(
         self,
-        context: RequestContext["ClientSession", Any],
+        context: RequestContext["ClientSession", Any, Any],
         params: types.CreateMessageRequestParams,
     ) -> types.CreateMessageResult | types.ErrorData: ...
 
 
 class ListRootsFnT(Protocol):
     async def __call__(
-        self, context: RequestContext["ClientSession", Any]
+        self, context: RequestContext["ClientSession", Any, Any]
     ) -> types.ListRootsResult | types.ErrorData: ...
 
 
@@ -53,7 +53,7 @@ async def _default_message_handler(
 
 
 async def _default_sampling_callback(
-    context: RequestContext["ClientSession", Any],
+    context: RequestContext["ClientSession", Any, Any],
     params: types.CreateMessageRequestParams,
 ) -> types.CreateMessageResult | types.ErrorData:
     return types.ErrorData(
@@ -63,7 +63,7 @@ async def _default_sampling_callback(
 
 
 async def _default_list_roots_callback(
-    context: RequestContext["ClientSession", Any],
+    context: RequestContext["ClientSession", Any, Any],
 ) -> types.ListRootsResult | types.ErrorData:
     return types.ErrorData(
         code=types.INVALID_REQUEST,
@@ -367,7 +367,7 @@ async def send_roots_list_changed(self) -> None:
     async def _received_request(
         self, responder: RequestResponder[types.ServerRequest, types.ClientResult]
     ) -> None:
-        ctx = RequestContext[ClientSession, Any](
+        ctx = RequestContext[ClientSession, Any, Any](
             request_id=responder.request_id,
             meta=responder.request_meta,
             session=self,

src/mcp/server/fastmcp/server.py

@@ -124,9 +124,11 @@ class Settings(BaseSettings, Generic[LifespanResultT]):
 def lifespan_wrapper(
     app: FastMCP,
     lifespan: Callable[[FastMCP], AbstractAsyncContextManager[LifespanResultT]],
-) -> Callable[[MCPServer[LifespanResultT]], AbstractAsyncContextManager[object]]:
+) -> Callable[
+    [MCPServer[LifespanResultT, Request]], AbstractAsyncContextManager[object]
+]:
     @asynccontextmanager
-    async def wrap(s: MCPServer[LifespanResultT]) -> AsyncIterator[object]:
+    async def wrap(s: MCPServer[LifespanResultT, Request]) -> AsyncIterator[object]:
         async with lifespan(app) as context:
             yield context
 
@@ -684,6 +686,7 @@ async def handle_sse(scope: Scope, receive: Receive, send: Send):
                     streams[0],
                     streams[1],
                     self._mcp_server.create_initialization_options(),
+                    request=request,
                 )
             return Response()
 
@@ -927,13 +930,14 @@ def my_tool(x: int, ctx: Context) -> str:
     The context is optional - tools that don't need it can omit the parameter.
     """
 
-    _request_context: RequestContext[ServerSessionT, LifespanContextT] | None
+    _request_context: RequestContext[ServerSessionT, LifespanContextT, Request] | None
     _fastmcp: FastMCP | None
 
     def __init__(
         self,
         *,
-        request_context: RequestContext[ServerSessionT, LifespanContextT] | None = None,
+        request_context: RequestContext[ServerSessionT, LifespanContextT, Request]
+        | None = None,
         fastmcp: FastMCP | None = None,
         **kwargs: Any,
     ):
@@ -949,7 +953,9 @@ def fastmcp(self) -> FastMCP:
         return self._fastmcp
 
     @property
-    def request_context(self) -> RequestContext[ServerSessionT, LifespanContextT]:
+    def request_context(
+        self,
+    ) -> RequestContext[ServerSessionT, LifespanContextT, Request]:
         """Access to the underlying request context."""
         if self._request_context is None:
             raise ValueError("Context is not available outside of a request")

src/mcp/server/lowlevel/server.py

@@ -83,7 +83,7 @@ async def main():
 from mcp.server.models import InitializationOptions
 from mcp.server.session import ServerSession
 from mcp.server.stdio import stdio_server as stdio_server
-from mcp.shared.context import RequestContext
+from mcp.shared.context import RequestContext, RequestT
 from mcp.shared.exceptions import McpError
 from mcp.shared.message import SessionMessage
 from mcp.shared.session import RequestResponder
@@ -93,7 +93,7 @@ async def main():
 LifespanResultT = TypeVar("LifespanResultT")
 
 # This will be properly typed in each Server instance's context
-request_ctx: contextvars.ContextVar[RequestContext[ServerSession, Any]] = (
+request_ctx: contextvars.ContextVar[RequestContext[ServerSession, Any, Any]] = (
     contextvars.ContextVar("request_ctx")
 )
 
@@ -111,7 +111,7 @@ def __init__(
 
 
 @asynccontextmanager
-async def lifespan(server: Server[LifespanResultT]) -> AsyncIterator[object]:
+async def lifespan(server: Server[LifespanResultT, RequestT]) -> AsyncIterator[object]:
     """Default lifespan context manager that does nothing.
 
     Args:
@@ -123,14 +123,15 @@ async def lifespan(server: Server[LifespanResultT]) -> AsyncIterator[object]:
     yield {}
 
 
-class Server(Generic[LifespanResultT]):
+class Server(Generic[LifespanResultT, RequestT]):
     def __init__(
         self,
         name: str,
         version: str | None = None,
         instructions: str | None = None,
         lifespan: Callable[
-            [Server[LifespanResultT]], AbstractAsyncContextManager[LifespanResultT]
+            [Server[LifespanResultT, RequestT]],
+            AbstractAsyncContextManager[LifespanResultT],
         ] = lifespan,
     ):
         self.name = name
@@ -215,7 +216,9 @@ def get_capabilities(
         )
 
     @property
-    def request_context(self) -> RequestContext[ServerSession, LifespanResultT]:
+    def request_context(
+        self,
+    ) -> RequestContext[ServerSession, LifespanResultT, RequestT]:
         """If called outside of a request context, this will raise a LookupError."""
         return request_ctx.get()
 
@@ -486,6 +489,7 @@ async def run(
         # but also make tracing exceptions much easier during testing and when using
         # in-process servers.
         raise_exceptions: bool = False,
+        request: RequestT | None = None,
         # When True, the server is stateless and
         # clients can perform initialization with any node. The client must still follow
         # the initialization lifecycle, but can do so with any available node
@@ -513,6 +517,7 @@ async def run(
                         session,
                         lifespan_context,
                         raise_exceptions,
+                        request,
                     )
 
     async def _handle_message(
@@ -523,6 +528,7 @@ async def _handle_message(
         session: ServerSession,
         lifespan_context: LifespanResultT,
         raise_exceptions: bool = False,
+        request: RequestT | None = None,
     ):
         with warnings.catch_warnings(record=True) as w:
             # TODO(Marcelo): We should be checking if message is Exception here.
@@ -532,7 +538,12 @@ async def _handle_message(
                 ):
                     with responder:
                         await self._handle_request(
-                            message, req, session, lifespan_context, raise_exceptions
+                            message,
+                            req,
+                            session,
+                            lifespan_context,
+                            raise_exceptions,
+                            request,
                         )
                 case types.ClientNotification(root=notify):
                     await self._handle_notification(notify)
@@ -547,6 +558,7 @@ async def _handle_request(
         session: ServerSession,
         lifespan_context: LifespanResultT,
         raise_exceptions: bool,
+        request: RequestT | None,
     ):
         logger.info(f"Processing request of type {type(req).__name__}")
         if type(req) in self.request_handlers:
@@ -563,6 +575,7 @@ async def _handle_request(
                         message.request_meta,
                         session,
                         lifespan_context,
+                        request=request,
                     )
                 )
                 response = await handler(req)

src/mcp/shared/context.py

@@ -8,11 +8,13 @@
 
 SessionT = TypeVar("SessionT", bound=BaseSession[Any, Any, Any, Any, Any])
 LifespanContextT = TypeVar("LifespanContextT")
+RequestT = TypeVar("RequestT")
 
 
 @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/memory.py

@@ -60,7 +60,7 @@ async def create_client_server_memory_streams() -> (
 
 @asynccontextmanager
 async def create_connected_server_and_client_session(
-    server: Server[Any],
+    server: Server[Any, Any],
     read_timeout_seconds: timedelta | None = None,
     sampling_callback: SamplingFnT | None = None,
     list_roots_callback: ListRootsFnT | None = None,

src/mcp/shared/progress.py

@@ -1,7 +1,7 @@
 from collections.abc import Generator
 from contextlib import contextmanager
 from dataclasses import dataclass, field
-from typing import Generic
+from typing import Any, Generic
 
 from pydantic import BaseModel
 
@@ -62,6 +62,7 @@ def progress(
             ReceiveNotificationT,
         ],
         LifespanContextT,
+        Any,
     ],
     total: float | None = None,
 ) -> Generator[

tests/client/test_list_roots_callback.py

@@ -30,7 +30,7 @@ async def test_list_roots_callback():
     )
 
     async def list_roots_callback(
-        context: RequestContext[ClientSession, None],
+        context: RequestContext[ClientSession, None, None],
     ) -> ListRootsResult:
         return callback_return
 

tests/client/test_sampling_callback.py

@@ -29,7 +29,7 @@ async def test_sampling_callback():
     )
 
     async def sampling_callback(
-        context: RequestContext[ClientSession, None],
+        context: RequestContext[ClientSession, None, None],
         params: CreateMessageRequestParams,
     ) -> CreateMessageResult:
         return callback_return