--- title: oauth sidebarTitle: oauth --- # `fastmcp.client.auth.oauth` ## Functions ### `default_cache_dir` ```python default_cache_dir() -> Path ``` ### `check_if_auth_required` ```python check_if_auth_required(mcp_url: str, httpx_kwargs: dict[str, Any] | None = None) -> bool ``` Check if the MCP endpoint requires authentication by making a test request. **Returns:** - True if auth appears to be required, False otherwise ## Classes ### `StoredToken` Token storage format with absolute expiry time. ### `FileTokenStorage` File-based token storage implementation for OAuth credentials and tokens. Implements the mcp.client.auth.TokenStorage protocol. Each instance is tied to a specific server URL for proper token isolation. **Methods:** #### `get_base_url` ```python get_base_url(url: str) -> str ``` Extract the base URL (scheme + host) from a URL. #### `get_cache_key` ```python get_cache_key(self) -> str ``` Generate a safe filesystem key from the server's base URL. #### `get_tokens` ```python get_tokens(self) -> OAuthToken | None ``` Load tokens from file storage. #### `set_tokens` ```python set_tokens(self, tokens: OAuthToken) -> None ``` Save tokens to file storage. #### `get_client_info` ```python get_client_info(self) -> OAuthClientInformationFull | None ``` Load client information from file storage. #### `set_client_info` ```python set_client_info(self, client_info: OAuthClientInformationFull) -> None ``` Save client information to file storage. #### `clear` ```python clear(self) -> None ``` Clear all cached data for this server. #### `clear_all` ```python clear_all(cls, cache_dir: Path | None = None) -> None ``` Clear all cached data for all servers. ### `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` ```python redirect_handler(self, authorization_url: str) -> None ``` Open browser for authorization. #### `callback_handler` ```python callback_handler(self) -> tuple[str, str | None] ``` Handle OAuth callback and return (auth_code, state).