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fastmcp.client.auth.oauth

Functions

check_if_auth_required

Check if the MCP endpoint requires authentication by making a test request. Returns:
  • True if auth appears to be required, False otherwise

Classes

ClientNotFoundError

Raised when OAuth client credentials are not found on the server.

TokenStorageAdapter

Methods:

clear

get_tokens

set_tokens

get_client_info

set_client_info

OAuth

OAuth client provider for MCP servers with browser-based authentication. This class provides OAuth authentication for FastMCP clients by opening a browser for user authorization and running a local callback server. Methods:

redirect_handler

Open browser for authorization, with pre-flight check for invalid client.

callback_handler

Handle OAuth callback and return (auth_code, state).

async_auth_flow

HTTPX auth flow with automatic retry on stale cached credentials. If the OAuth flow fails due to invalid/stale client credentials, clears the cache and retries once with fresh registration.