New in version: 2.2.11

​
Overview

When running FastMCP as a web server, your MCP tools, resources, and prompts might need to access the underlying HTTP request information, such as headers, client IP, or query parameters.

FastMCP provides a clean way to access HTTP request information through a dependency function.

​
Accessing HTTP Requests

The recommended way to access the current HTTP request is through the get_http_request() dependency function:

from fastmcp import FastMCP
from fastmcp.server.dependencies import get_http_request
from starlette.requests import Request

mcp = FastMCP(name="HTTPRequestDemo")

@mcp.tool()
async def user_agent_info() -> dict:
    """Return information about the user agent."""
    # Get the HTTP request
    request: Request = get_http_request()
    
    # Access request data
    user_agent = request.headers.get("user-agent", "Unknown")
    client_ip = request.client.host if request.client else "Unknown"
    
    return {
        "user_agent": user_agent,
        "client_ip": client_ip,
        "path": request.url.path,
    }

This approach works anywhere within a request’s execution flow, not just within your MCP function. It’s useful when:

  1. You need access to HTTP information in helper functions
  2. You’re calling nested functions that need HTTP request data
  3. You’re working with middleware or other request processing code

​
Important Notes

  • HTTP requests are only available when FastMCP is running as part of a web application
  • Accessing the HTTP request outside of a web request context will raise a RuntimeError
  • The get_http_request() function returns a standard Starlette Request object

​
Common Use Cases

​
Accessing Request Headers

from fastmcp.server.dependencies import get_http_request

@mcp.tool()
async def get_auth_info() -> dict:
    """Get authentication information from request headers."""
    request = get_http_request()
    
    # Get authorization header
    auth_header = request.headers.get("authorization", "")
    
    # Check for Bearer token
    is_bearer = auth_header.startswith("Bearer ")
    
    return {
        "has_auth": bool(auth_header),
        "auth_type": "Bearer" if is_bearer else "Other" if auth_header else "None"
    }