The character encoding of the stdin/stdout streams in Python is platform-
dependent. On Windows it will be something weird, like CP437 or CP1252,
depending on the locale. This change ensures that no matter the platform,
UTF-8 is used.
- Add proper generic parameter for lifespan context type
- Update README with TypedDict example for strong typing
- Fix context variable initialization in server
- Improve property return type safety
- Remove redundant documentation
- Ensure compatibility with existing tests
Adds support for the lifespan API to FastMCP server, enabling:
- Simple setup with FastMCP constructor
- Type-safe context passing to tools and handlers
- Configuration via Settings class
Adds a context manager based lifespan API in mcp.server.lowlevel.server to manage server lifecycles in a
type-safe way. This enables servers to:
- Initialize resources on startup and clean them up on shutdown
- Pass context data from startup to request handlers
- Support async startup/shutdown operations
This commit adds support for request cancellation and tracking of
in-flight requests in the MCP protocol implementation. The key
architectural changes are:
1. Request Lifecycle Management:
- Added _in_flight dictionary to BaseSession to track active requests
- Requests are tracked from receipt until completion/cancellation
- Added proper cleanup via on_complete callback
2. Cancellation Support:
- Added CancelledNotification handling in _receive_loop
- Implemented cancel() method in RequestResponder
- Uses anyio.CancelScope for robust cancellation
- Sends error response on cancellation
3. Request Context:
- Added request_ctx ContextVar for request context
- Ensures proper cleanup after request handling
- Maintains request state throughout lifecycle
4. Error Handling:
- Improved error propagation for cancelled requests
- Added proper cleanup of cancelled requests
- Maintains consistency of in-flight tracking
This change enables clients to cancel long-running requests and
servers to properly clean up resources when requests are cancelled.
Github-Issue:#88
Introduce ReadResourceContents type to properly handle MIME types in resource responses. Breaking change in FastMCP read_resource() return type.
Github-Issue:#152
The server was ignoring mime types set on resources, defaulting to text/plain
for strings and application/octet-stream for bytes. Now properly preserves
the specified mime type in both FastMCP and low-level server implementations.
Note that this is breaks backwards compatibility as it changes the return
values of read_resource() on FastMCP. It is BC compatible on lowlevel since
it only extends the callback.
Github-Issue: #152
Reported-by: eiseleMichael
This commit integrates FastMCP, a high-level MCP server implementation originally written by Jeremiah Lowin,
into the official MCP SDK. It also updates dependencies and adds new dev dependencies.
It moves the existing SDK into a .lowlevel .
We missed to have a handler for resource templates. We add this
now. One caveat is still that the `uriTemplate` in `ResourceTemplate`
is not a pydantic type.
Add methods to track and verify client capabilities during initialization. This
includes storing client parameters from the initialize request and providing a
check_client_capability method to verify if specific capabilities are supported
by the connected client.
We currently return a generic instance of RequestContext without
a specialization on the Session type. This makes it impossible
for servers to typesafe call `list_roots()` and other methods.
We now return a specific instance of `RequestContext[ServerSession]`
We will be a bit more low level and expect callees to import mcp.types
instead of relying in re-exported types. This makes usage more explicit
and avoids potential collisions in mcp.server.
