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fastmcp.server.http

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Functions

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set_http_request

set_http_request(request: Request) -> Generator[Request, None, None]

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create_base_app

create_base_app(routes: list[BaseRoute], middleware: list[Middleware], debug: bool = False, lifespan: Callable | None = None) -> StarletteWithLifespan

• routes: List of routes to include in the app
• middleware: List of middleware to include in the app
• debug: Whether to enable debug mode
• lifespan: Optional lifespan manager for the app

• A Starlette application

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create_sse_app

create_sse_app(server: FastMCP[LifespanResultT], message_path: str, sse_path: str, auth: AuthProvider | None = None, debug: bool = False, routes: list[BaseRoute] | None = None, middleware: list[Middleware] | None = None, host_origin_protection: HostOriginProtection = False, allowed_hosts: Sequence[str] | None = None, allowed_origins: Sequence[str] | None = None) -> StarletteWithLifespan

• server: The FastMCP server instance
• message_path: Path for SSE messages
• sse_path: Path for SSE connections
• auth: Optional authentication provider (AuthProvider)
• debug: Whether to enable debug mode
• routes: Optional list of custom routes
• middleware: Optional list of middleware
• host_origin_protection: Whether to validate Host and Origin headers before requests reach the SSE connection and message endpoints. Defaults to False for compatibility. “auto” protects localhost-bound servers and explicit host/origin allowlists.
• allowed_hosts: Additional hostnames that may appear in the Host header.
• allowed_origins: Additional browser origins trusted by the request guard. Configure CORS separately when browser JavaScript must read cross-origin responses.

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create_streamable_http_app

create_streamable_http_app(server: FastMCP[LifespanResultT], streamable_http_path: str, event_store: EventStore | None = None, retry_interval: int | None = None, auth: AuthProvider | None = None, json_response: bool = False, stateless_http: bool = False, debug: bool = False, routes: list[BaseRoute] | None = None, middleware: list[Middleware] | None = None, host_origin_protection: HostOriginProtection = False, allowed_hosts: Sequence[str] | None = None, allowed_origins: Sequence[str] | None = None, session_idle_timeout: float | Literal['auto'] | None = 'auto') -> StarletteWithLifespan

• server: The FastMCP server instance
• streamable_http_path: Path for StreamableHTTP connections
• event_store: Optional event store for SSE polling/resumability
• 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. Defaults to SDK default.
• auth: Optional authentication provider (AuthProvider)
• json_response: Whether to use JSON response format
• stateless_http: Whether to use stateless mode (new transport per request)
• debug: Whether to enable debug mode
• routes: Optional list of custom routes
• middleware: Optional list of middleware
• host_origin_protection: Whether to validate Host and Origin headers before requests reach the MCP endpoint. Defaults to False for compatibility. “auto” protects localhost-bound servers and explicit host/origin allowlists.
• allowed_hosts: Additional hostnames that may appear in the Host header.
• allowed_origins: Additional browser origins trusted by the request guard. Configure CORS separately when browser JavaScript must read cross-origin responses.
• session_idle_timeout: Maximum time in seconds a session may remain idle before it is terminated. The deadline is pushed forward on every request. Defaults to “auto”, which uses the MCP SDK’s default (1800 seconds as of SDK 2.2). When None, sessions never expire from inactivity. Only applies to stateful HTTP sessions.

• A Starlette application with StreamableHTTP support

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Classes

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FastMCPStreamableHTTPSessionManager

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event_store

event_store(self) -> EventStore | None

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event_store

event_store(self, event_store: EventStore | None) -> None

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StreamableHTTPASGIApp

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HostOriginGuardMiddleware

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StarletteWithLifespan

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lifespan

lifespan(self) -> Lifespan[Starlette]

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RequestContextMiddleware