---
title: oauth
sidebarTitle: oauth
---
# `fastmcp.client.auth.oauth`
## Functions
### `default_cache_dir`
```python
default_cache_dir() -> Path
```
### `discover_oauth_metadata`
```python
discover_oauth_metadata(server_base_url: str, httpx_kwargs: dict[str, Any] | None = None) -> OAuthMetadata | None
```
Discover OAuth metadata from the server using RFC 8414 well-known endpoint.
**Args:**
- `server_base_url`: Base URL of the OAuth server (e.g., "https\://example.com")
- `httpx_kwargs`: Additional kwargs for httpx client
**Returns:**
- OAuth metadata if found, None otherwise
### `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
### `OAuth`
```python
OAuth(mcp_url: str, scopes: str | list[str] | None = None, client_name: str = 'FastMCP Client', token_storage_cache_dir: Path | None = None, additional_client_metadata: dict[str, Any] | None = None) -> OAuthClientProvider
```
Create an OAuthClientProvider for an MCP server.
This is intended to be provided to the `auth` parameter of an
httpx.AsyncClient (or appropriate FastMCP client/transport instance)
**Args:**
- `mcp_url`: Full URL to the MCP endpoint (e.g. "http\://host/mcp/sse/")
- `scopes`: OAuth scopes to request. Can be a
- `client_name`: Name for this client during registration
- `token_storage_cache_dir`: Directory for FileTokenStorage
- `additional_client_metadata`: Extra fields for OAuthClientMetadata
**Returns:**
- OAuthClientProvider
## Classes
### `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.