fastmcp/docs/patterns/http-requests.mdx
2025-05-06 22:06:33 -04:00

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---
title: HTTP Requests
sidebarTitle: HTTP Requests
description: Accessing and using HTTP requests in FastMCP servers
icon: network-wired
---
import { VersionBadge } from '/snippets/version-badge.mdx'
<VersionBadge 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:
```python {2, 3, 11}
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](https://www.starlette.io/requests/) object
## Common Use Cases
### Accessing Request Headers
```python
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"
}
```