> ## Documentation Index
> Fetch the complete documentation index at: https://gofastmcp.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Descope 🤝 FastMCP

> Secure your FastMCP server with Descope

export const VersionBadge = ({version}) => {
  return <Badge stroke size="lg" icon="gift" iconType="regular" className="version-badge">
            New in version <code>{version}</code>
        </Badge>;
};

<VersionBadge version="2.12.4" />

This guide shows you how to secure your FastMCP server using [**Descope**](https://www.descope.com), a complete authentication and user management solution. This integration uses the [**Remote OAuth**](/servers/auth/remote-oauth) pattern, where Descope handles user login and your FastMCP server validates the tokens.

## Configuration

### Prerequisites

Before you begin, you will need:

1. To [sign up](https://www.descope.com/sign-up) for a Free Forever Descope account
2. Your FastMCP server's URL (can be localhost for development, e.g., `http://localhost:8000`)

### Step 1: Configure Descope

<Steps>
  <Step title="Configure a Descope application">
    You can use either a resource-specific Descope MCP Server or a project-level inbound app.

    To create an MCP Server, go to the [MCP Servers page](https://app.descope.com/mcp-servers) of the Descope Console, create a server, and enable **Dynamic Client Registration (DCR)**.

    <Warning>
      DCR is required for FastMCP clients to automatically register with your authentication server.
    </Warning>
  </Step>

  <Step title="Copy the Well-Known URL">
    `DescopeProvider` accepts both resource-specific MCP Server URLs:

    ```
    https://api.descope.com/v1/apps/agentic/P.../M.../.well-known/openid-configuration
    ```

    and project-level inbound app URLs:

    ```
    https://api.descope.com/v1/apps/P.../.well-known/openid-configuration
    ```
  </Step>
</Steps>

### Step 2: Environment Setup

Create a `.env` file with your Descope configuration:

```bash theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
DESCOPE_CONFIG_URL=https://api.descope.com/v1/apps/P.../.well-known/openid-configuration
BASE_URL=http://localhost:8000
```

### Step 3: FastMCP Configuration

Create your FastMCP server file and use the DescopeProvider to handle all the OAuth integration automatically. Nothing reads `.env` automatically, so load it explicitly with [python-dotenv](https://pypi.org/project/python-dotenv/) (`pip install python-dotenv`) before constructing the provider — otherwise the values you just wrote stay invisible to `os.environ`.

```python server.py theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
import os

from dotenv import load_dotenv
from fastmcp import FastMCP
from fastmcp.server.auth.providers.descope import DescopeProvider

load_dotenv()

# DescopeProvider accepts either supported Well-Known URL format.
auth_provider = DescopeProvider(
    config_url=os.environ["DESCOPE_CONFIG_URL"],
    base_url=os.environ.get("BASE_URL", "http://localhost:8000"),
)

# Create FastMCP server with auth
mcp = FastMCP(name="My Descope Protected Server", auth=auth_provider)
```

### Scope discovery and validation

<VersionBadge version="4.0.0" />

When both `scopes_supported` and `required_scopes` are omitted, `DescopeProvider` discovers `scopes_supported` lazily from the OpenID configuration and advertises them to MCP clients. Provider construction remains network-free, and a transient discovery failure is retried on a later metadata request.

Set both options when clients should request a broader set of scopes than the server requires on every token:

```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
from fastmcp.server.auth.providers.descope import DescopeProvider

auth_provider = DescopeProvider(
    config_url="https://api.descope.com/v1/apps/P.../.well-known/openid-configuration",
    base_url="https://your-fastmcp-server.com",
    scopes_supported=["mcp:read", "mcp:write"],
    required_scopes=["mcp:read"],
)
```

`scopes_supported` controls what the protected resource metadata advertises. `required_scopes` controls what the JWT verifier requires during token validation. When only `required_scopes` is set, those scopes are also advertised to clients.

## Testing

To test your server, you can use the `fastmcp` CLI to run it locally. Assuming you've saved the above code to `server.py` (after replacing the environment variables with your actual values!), you can run the following command:

```bash theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
fastmcp run server.py --transport http --port 8000
```

Now, you can use a FastMCP client to test that you can reach your server after authenticating:

```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
from fastmcp import Client
import asyncio

async def main():
    async with Client("http://localhost:8000/mcp", auth="oauth") as client:
        tools = await client.list_tools()
        print(f"Authenticated. Server exposes {len(tools)} tools.")

if __name__ == "__main__":
    asyncio.run(main())
```

## Production Configuration

For production deployments, load configuration from environment variables:

```python server.py theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
import os
from fastmcp import FastMCP
from fastmcp.server.auth.providers.descope import DescopeProvider

# Load configuration from environment variables
auth = DescopeProvider(
    config_url=os.environ.get("DESCOPE_CONFIG_URL"),
    base_url=os.environ.get("BASE_URL", "https://your-server.com")
)

mcp = FastMCP(name="My Descope Protected Server", auth=auth)
```