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87 lines
No EOL
3.1 KiB
Text
---
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title: HTTP Requests
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sidebarTitle: HTTP Requests
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description: Accessing and using HTTP requests in FastMCP servers
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icon: network-wired
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---
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import { VersionBadge } from '/snippets/version-badge.mdx'
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<VersionBadge version="2.2.11" />
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## Overview
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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.
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FastMCP provides a clean way to access HTTP request information through a dependency function.
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## Accessing HTTP Requests
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The recommended way to access the current HTTP request is through the `get_http_request()` dependency function:
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```python {2, 3, 11}
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from fastmcp import FastMCP
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from fastmcp.server.dependencies import get_http_request
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from starlette.requests import Request
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mcp = FastMCP(name="HTTP Request Demo")
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@mcp.tool
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async def user_agent_info() -> dict:
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"""Return information about the user agent."""
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# Get the HTTP request
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request: Request = get_http_request()
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# Access request data
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user_agent = request.headers.get("user-agent", "Unknown")
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client_ip = request.client.host if request.client else "Unknown"
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return {
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"user_agent": user_agent,
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"client_ip": client_ip,
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"path": request.url.path,
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}
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```
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This approach works anywhere within a request's execution flow, not just within your MCP function. It's useful when:
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1. You need access to HTTP information in helper functions
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2. You're calling nested functions that need HTTP request data
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3. You're working with middleware or other request processing code
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## Accessing HTTP Headers Only
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If you only need request headers and want to avoid potential errors, you can use the `get_http_headers()` helper:
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```python {2}
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from fastmcp import FastMCP
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from fastmcp.server.dependencies import get_http_headers
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mcp = FastMCP(name="Headers Demo")
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@mcp.tool
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async def safe_header_info() -> dict:
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"""Safely get header information without raising errors."""
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# Get headers (returns empty dict if no request context)
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headers = get_http_headers()
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# Get authorization header
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auth_header = headers.get("authorization", "")
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is_bearer = auth_header.startswith("Bearer ")
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return {
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"user_agent": headers.get("user-agent", "Unknown"),
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"content_type": headers.get("content-type", "Unknown"),
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"has_auth": bool(auth_header),
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"auth_type": "Bearer" if is_bearer else "Other" if auth_header else "None",
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"headers_count": len(headers)
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}
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```
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By default, `get_http_headers()` excludes problematic headers like `host` and `content-length`. To include all headers, use `get_http_headers(include_all=True)`.
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## Important Notes
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- HTTP requests are only available when FastMCP is running as part of a web application
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- Accessing the HTTP request with `get_http_request()` outside of a web request context will raise a `RuntimeError`
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- The `get_http_headers()` function **never raises errors** - it returns an empty dict when no request context is available
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- The `get_http_request()` function returns a standard [Starlette Request](https://www.starlette.io/requests/) object |