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mcp-websocket-empty-url ​

MCP WebSocket transport URL cannot be empty

Error

Rule Details ​

This rule checks that MCP servers configured with type "websocket" include a url field that is present and non-empty. A missing or blank URL means Claude Code cannot establish a WebSocket connection to the MCP server, resulting in connection failures at runtime.

Incorrect ​

WebSocket server with an empty URL string

json
{
  "mcpServers": {
    "realtime": {
      "type": "websocket",
      "url": ""
    }
  }
}

WebSocket server with the url field missing

json
{
  "mcpServers": {
    "realtime": {
      "type": "websocket"
    }
  }
}

Correct ​

WebSocket server with a valid URL

json
{
  "mcpServers": {
    "realtime": {
      "type": "websocket",
      "url": "wss://mcp.example.com/ws"
    }
  }
}

How To Fix ​

Add a non-empty url field to the WebSocket server configuration. The URL should use the ws:// or wss:// protocol scheme.

Options ​

This rule does not have any configuration options.

Resources ​

Version ​

Available since: v0.2.0