docs/python-sdk/fastmcp-client-auth-oauth.mdx

---
title: oauth
sidebarTitle: oauth
---

# `fastmcp.client.auth.oauth`

## Functions

### `default_cache_dir` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L35" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
default_cache_dir() -> Path
```

### `discover_oauth_metadata` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L153" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```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` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L188" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```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` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L218" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```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` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L39" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


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` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L54" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
get_base_url(url: str) -> str
```

Extract the base URL (scheme + host) from a URL.


#### `get_cache_key` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L59" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
get_cache_key(self) -> str
```

Generate a safe filesystem key from the server's base URL.


#### `get_tokens` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L74" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
get_tokens(self) -> OAuthToken | None
```

Load tokens from file storage.


#### `set_tokens` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L91" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
set_tokens(self, tokens: OAuthToken) -> None
```

Save tokens to file storage.


#### `get_client_info` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L97" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
get_client_info(self) -> OAuthClientInformationFull | None
```

Load client information from file storage.


#### `set_client_info` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L125" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
set_client_info(self, client_info: OAuthClientInformationFull) -> None
```

Save client information to file storage.


#### `clear` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L131" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
clear(self) -> None
```

Clear all cached data for this server.


#### `clear_all` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L140" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
clear_all(cls, cache_dir: Path | None = None) -> None
```

Clear all cached data for all servers.