---
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#L38" target="_blank">↗</a></sup>

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

### `OAuth` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L295" target="_blank">↗</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) -> _MCPOAuthClientProvider
```


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

### `ServerOAuthMetadata` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L43" target="_blank">↗</a></sup>


More flexible OAuth metadata model that accepts broader ranges of values
than the restrictive MCP standard model.

This handles real-world OAuth servers like PayPal that may support
additional methods not in the MCP specification.


### `OAuthClientProvider` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L68" target="_blank">↗</a></sup>


OAuth client provider with more flexible OAuth metadata discovery.


### `FileTokenStorage` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L116" target="_blank">↗</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#L131" target="_blank">↗</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#L136" target="_blank">↗</a></sup>

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

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


#### `clear` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/client/auth/oauth.py#L208" target="_blank">↗</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#L217" target="_blank">↗</a></sup>

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

Clear all cached data for all servers.

