Streamable HTTP Transport

What is Streamable HTTP Transport?

Streamable HTTP transport is a modern communication protocol for MCP that uses standard HTTP requests with the ability to support streaming responses. It provides several advantages:

• Direct HTTP Communication: Connect to your Drupal site without additional binaries or Docker containers
• Remote Access: Easily connect to publicly accessible Drupal sites
• Future Streaming Support: Designed to support Server-Sent Events (SSE) for real-time communication

Current Implementation

The Drupal MCP module currently supports HTTP transport without streaming capabilities. Full streaming support with Server-Sent Events (SSE) will be added in a future release. This means you can use all MCP features through standard HTTP POST requests, but real-time server-to-client communication is not yet available.

Security

• Always use HTTPS in production environments
• Users must have the “Use MCP server” permission in Drupal
• Create dedicated MCP user accounts with only necessary permissions

Configuration Examples

Claude Desktop

Claude Desktop doesn’t natively support HTTP transport yet, but you can use the mcp-remote package as a bridge:

{
  "mcpServers": {
    "mcp-server-drupal": {
      "command": "npx",
      "args": [
        "mcp-remote",
        "https://your-drupal-site.com/mcp/post",
        "--transport",
        "http-only",
        "-y"
      ]
    }
  }
}

Replace https://your-drupal-site.com/mcp/post with your actual Drupal site URL. The /mcp/post endpoint is the standard MCP HTTP endpoint provided by the Drupal module.

Cursor

Cursor has native support for streamable HTTP transport:

{
  "mcpServers": {
    "mcp-server-drupal": {
      "type": "streamable-http",
      "url": "https://your-drupal-site.com/mcp/post"
    }
  }
}

This configuration is simpler and doesn’t require additional packages.

Authentication

HTTP transport supports the same authentication methods as STDIO transport:

Token Authentication

Configure token authentication in your Drupal MCP settings and include the token in your client configuration:

{
  "mcpServers": {
    "mcp-server-drupal": {
      "type": "streamable-http",
      "url": "https://your-drupal-site.com/mcp/post",
      "headers": {
        "Authorization": "Basic BASE64_ENCODED_TOKEN"
      }
    }
  }
}

Where BASE64_ENCODED_TOKEN is the base64 encoding of your token. The Drupal MCP authentication provider expects all authentication to use the Basic auth format.

Basic Authentication

For basic authentication, use the standard HTTP Basic authentication header format:

{
  "mcpServers": {
    "mcp-server-drupal": {
      "type": "streamable-http",
      "url": "https://your-drupal-site.com/mcp/post",
      "headers": {
        "Authorization": "Basic BASE64_ENCODED_CREDENTIALS"
      }
    }
  }
}

Where BASE64_ENCODED_CREDENTIALS is the base64 encoding of username:password.

Troubleshooting

Connection Issues

If you’re having trouble connecting:

1. Verify the URL: Ensure your Drupal site URL is correct and includes /mcp/post
2. Check Authentication: Confirm authentication is enabled in MCP settings
3. Test Access: Try accessing https://your-site.com/mcp/post in a browser (should return a method not allowed error)
4. CORS Configuration: For browser-based clients, ensure CORS is properly configured

Common Errors

• 404 Not Found: The MCP module might not be enabled or the URL is incorrect
• 401 Unauthorized: Authentication credentials are missing or incorrect
• 403 Forbidden: The user doesn’t have the “Use MCP server” permission
• 500 Server Error: Check Drupal logs for specific error messages

Next Steps

Now that you’ve configured HTTP transport, you can:

• Test your connection by querying available tools
• Start using MCP features to interact with your Drupal site
• Monitor your Drupal logs for MCP activity
• Explore what else you can do with MCP