Class Context

src/mcp/server/mcpserver/context.py:25–308

Context object providing access to MCP capabilities. This provides a cleaner interface to MCP's RequestContext functionality. It gets injected into tool and resource functions that request it via type hints. To use context in a tool function, add a parameter with the Context type annot

class Context(BaseModel, Generic[LifespanContextT, RequestT]):
    """Context object providing access to MCP capabilities.

    This provides a cleaner interface to MCP's RequestContext functionality.
    It gets injected into tool and resource functions that request it via type hints.

    To use context in a tool function, add a parameter with the Context type annotation:

    ```python
    @server.tool()
    async def my_tool(x: int, ctx: Context) -> str:
        # Log messages to the client
        await ctx.info(f"Processing {x}")
        await ctx.debug("Debug info")
        await ctx.warning("Warning message")
        await ctx.error("Error message")

        # Report progress
        await ctx.report_progress(50, 100)

        # Access resources
        data = await ctx.read_resource("resource://data")

        # Get request info
        request_id = ctx.request_id
        client_id = ctx.client_id

        return str(x)
    ```

    The context parameter name can be anything as long as it's annotated with Context.
    The context is optional - tools that don't need it can omit the parameter.
    """

    _request_context: ServerRequestContext[LifespanContextT, RequestT] | None
    _mcp_server: MCPServer | None
    _input_params: InputResponseRequestParams | None

    # TODO(maxisbey): Consider making request_context/mcp_server required, or refactor Context entirely.
    def __init__(
        self,
        *,
        request_context: ServerRequestContext[LifespanContextT, RequestT] | None = None,
        mcp_server: MCPServer | None = None,
        input_params: InputResponseRequestParams | None = None,
        # TODO(Marcelo): We should drop this kwargs parameter.
        **kwargs: Any,
    ):
        super().__init__(**kwargs)
        self._request_context = request_context
        self._mcp_server = mcp_server
        self._input_params = input_params

    @property
    def mcp_server(self) -> MCPServer:
        """Access to the MCPServer instance."""
        if self._mcp_server is None:  # pragma: no cover
            raise ValueError("Context is not available outside of a request")