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fastmcp.server.mixins.transport

Transport-related methods for FastMCP Server.

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Classes

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TransportMixin

Mixin providing transport-related methods for FastMCP. Includes HTTP/stdio/SSE transport handling and custom HTTP routes. Methods:

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run_async 

run_async(self: FastMCP, transport: Transport | None = None, show_banner: bool | None = None, **transport_kwargs: Any) -> None
Run the FastMCP server asynchronously. Args:
  • transport: Transport protocol to use (“stdio”, “http”, “sse”, or “streamable-http”)
  • show_banner: Whether to display the server banner. If None, uses the FASTMCP_SHOW_SERVER_BANNER setting (default: True).

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run 

run(self: FastMCP, transport: Transport | None = None, show_banner: bool | None = None, **transport_kwargs: Any) -> None
Run the FastMCP server. Note this is a synchronous function. Args:
  • transport: Transport protocol to use (“http”, “stdio”, “sse”, or “streamable-http”)
  • show_banner: Whether to display the server banner. If None, uses the FASTMCP_SHOW_SERVER_BANNER setting (default: True).

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custom_route 

custom_route(self: FastMCP, path: str, methods: list[str], name: str | None = None, include_in_schema: bool = True) -> Callable[[Callable[[Request], Awaitable[Response]]], Callable[[Request], Awaitable[Response]]]
Decorator to register a custom HTTP route on the FastMCP server. Allows adding arbitrary HTTP endpoints outside the standard MCP protocol, which can be useful for OAuth callbacks, health checks, or admin APIs. The handler function must be an async function that accepts a Starlette Request and returns a Response. Args:
  • path: URL path for the route (e.g., “/auth/callback”)
  • methods: List of HTTP methods to support (e.g., [“GET”, “POST”])
  • name: Optional name for the route (to reference this route with Starlette’s reverse URL lookup feature)
  • include_in_schema: Whether to include in OpenAPI schema, defaults to True

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run_stdio_async 

run_stdio_async(self: FastMCP, show_banner: bool = True, log_level: str | None = None, stateless: bool = False) -> None
Run the server using stdio transport. Args:
  • show_banner: Whether to display the server banner
  • log_level: Log level for the server
  • stateless: Whether to run in stateless mode (no session initialization)

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run_http_async 

run_http_async(self: FastMCP, show_banner: bool = True, transport: Literal['http', 'streamable-http', 'sse'] = 'http', host: str | None = None, port: int | None = None, log_level: str | None = None, path: str | None = None, uvicorn_config: dict[str, Any] | None = None, middleware: list[ASGIMiddleware] | None = None, json_response: bool | None = None, stateless_http: bool | None = None, stateless: bool | None = None) -> None
Run the server using HTTP transport. Args:
  • transport: Transport protocol to use - “http” (default), “streamable-http”, or “sse”
  • host: Host address to bind to (defaults to settings.host)
  • port: Port to bind to (defaults to settings.port)
  • log_level: Log level for the server (defaults to settings.log_level)
  • path: Path for the endpoint (defaults to settings.streamable_http_path or settings.sse_path)
  • uvicorn_config: Additional configuration for the Uvicorn server
  • middleware: A list of middleware to apply to the app
  • json_response: Whether to use JSON response format (defaults to settings.json_response)
  • stateless_http: Whether to use stateless HTTP (defaults to settings.stateless_http)
  • stateless: Alias for stateless_http for CLI consistency

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http_app 

http_app(self: FastMCP, path: str | None = None, middleware: list[ASGIMiddleware] | None = None, json_response: bool | None = None, stateless_http: bool | None = None, transport: Literal['http', 'streamable-http', 'sse'] = 'http', event_store: EventStore | None = None, retry_interval: int | None = None) -> StarletteWithLifespan
Create a Starlette app using the specified HTTP transport. Args:
  • path: The path for the HTTP endpoint
  • middleware: A list of middleware to apply to the app
  • json_response: Whether to use JSON response format
  • stateless_http: Whether to use stateless mode (new transport per request)
  • transport: Transport protocol to use - “http”, “streamable-http”, or “sse”
  • event_store: Optional event store for SSE polling/resumability. When set, enables clients to reconnect and resume receiving events after server-initiated disconnections. Only used with streamable-http transport.
  • retry_interval: Optional retry interval in milliseconds for SSE polling. Controls how quickly clients should reconnect after server-initiated disconnections. Requires event_store to be set. Only used with streamable-http transport.
Returns:
  • A Starlette application configured with the specified transport