Cursor MCP Servers settings shows "No tools available" for @21st-dev/magic

Cursor MCP Server Shows "No tools available" for `@21st-dev/magic`

When configuring Cursor's MCP (Managed Code Provider) servers, the `@21st-dev/magic` tool is not being recognized, resulting in the "No tools available" message within the Cursor interface. Despite a seemingly correct configuration in the ~/.cursor/mcp.json file, Cursor fails to identify and utilize the tool's capabilities.

The core problem lies in how the `@21st-dev/magic` MCP server is being launched and how it communicates with Cursor. The provided MCP logs indicate a failure to establish a stable connection, leading to the "Connection closed" error. The "No server info found" error further suggests that Cursor is unable to properly initialize and maintain a connection with the `@21st-dev/magic` server.

Root Cause Analysis

While the exact root cause requires further investigation, several potential issues could be contributing to the problem:

• Incorrect Argument Handling: The API_KEY="xxxxxxxxxx" argument might not be correctly passed or interpreted by the `@21st-dev/magic` tool. Environment variables are often a more robust way to pass sensitive information.
• Process Termination: The npx command might be terminating prematurely if `@21st-dev/magic` doesn't maintain a persistent connection or encounters an error during initialization.
• MCP Protocol Incompatibility: The `@21st-dev/magic` tool might not be fully compliant with the MCP protocol expected by Cursor, especially regarding the exchange of server information and tool offerings.
• Version Incompatibility: The @latest tag might be pulling a version of `@21st-dev/magic` that is incompatible with the current version of Cursor's MCP implementation.

Solution

Here's a step-by-step approach to troubleshoot and resolve the issue:

1. Environment Variable Configuration: Modify the mcp.json configuration to use an environment variable for the API key. First, set the environment variable in your shell (e.g., export MAGIC_API_KEY="xxxxxxxxxx"). Then, update the mcp.json file:

{
  "mcpServers": {
    "@21st-dev/magic": {
      "command": "npx",
      "args": [
        "-y",
        "@21st-dev/magic@latest"
      ],
      "env": {
        "API_KEY": "$MAGIC_API_KEY"
      }
    }
  }
}

2. Pin a Specific Version: Replace @latest with a specific, known-working version of `@21st-dev/magic`. This helps isolate version incompatibility issues:

{
  "mcpServers": {
    "@21st-dev/magic": {
      "command": "npx",
      "args": [
        "-y",
        "@21st-dev/magic@1.2.3"
      ],
      "env": {
        "API_KEY": "$MAGIC_API_KEY"
      }
    }
  }
}

3. Verify MCP Compliance: Ensure that `@21st-dev/magic` correctly implements the MCP protocol, including proper handling of ListOfferings requests and the establishment of a persistent connection. Refer to Cursor's MCP documentation or examples for guidance.
4. Examine `@21st-dev/magic` Output: Modify the command and args to redirect the output of `@21st-dev/magic` to a file. This can provide valuable debugging information:

{
  "mcpServers": {
    "@21st-dev/magic": {
      "command": "bash",
      "args": [
        "-c",
        "npx -y @21st-dev/magic@latest API_KEY=\"$MAGIC_API_KEY\" > /tmp/magic_mcp.log 2>&1"
      ]
    }
  }
}

Then, examine the contents of /tmp/magic_mcp.log for any error messages or unexpected behavior.

5. Restart Cursor: After making any changes to mcp.json, restart Cursor to ensure the new configuration is loaded.

Practical Tips and Considerations

• MCP Server Stability: Ensure that the MCP server process remains active and responsive after initialization. Cursor relies on a persistent connection to the server.
• Error Handling: Implement robust error handling within the `@21st-dev/magic` tool to gracefully handle unexpected situations and provide informative error messages to Cursor.
• Logging: Incorporate comprehensive logging within `@21st-dev/magic` to aid in debugging and troubleshooting connection issues.
• Consult Documentation: Refer to both Cursor's MCP documentation and `@21st-dev/magic`'s documentation for specific requirements and best practices.
• Test with a Minimal Configuration: Start with a very simple configuration of `@21st-dev/magic` to rule out complex configuration issues. Gradually add complexity as you verify each component.