Cursor MCP Not Working: Troubleshooting Connection, Path, and JSON Configuration Errors

Connecting external Model Context Protocol (MCP) servers to Cursor extends the IDE’s capabilities with custom database schemas, API connectors, and terminal tools.

However, developers frequently run into red “Disconnected” status indicators, silent tool failures, or environment path errors. This guide details how to diagnose and fix Cursor MCP integration issues quickly.

Cursor MCP Error Diagnostics Matrix

 ┌────────────────────────────────────────────────────────────────────────┐
 │                   CURSOR MCP CONNECTION DIAGNOSTICS                    │
 └───────────────────────────────────┬────────────────────────────────────┘
                                     │
           ┌─────────────────────────┼─────────────────────────┐
           ▼                         ▼                         ▼
┌──────────────────────┐  ┌──────────────────────┐  ┌──────────────────────┐
│  RED DISCONNECTED    │  │  MISSING PATH / NPX  │  │  JSON SYNTAX ERROR   │
├──────────────────────┤  ├──────────────────────┤  ├──────────────────────┤
│ • Check process logs │  │ • Use absolute paths │  │ • Validate JSON schema│
│ • Restart Cursor IDE │  │ • `/usr/local/bin`   │  │ • Fix trailing commas│
└──────────────────────┘  └──────────────────────┘  └──────────────────────┘

1. Fix: Replacing Relative Commands with Absolute Paths

When GUI applications like Cursor launch on macOS or Windows, they do not inherit interactive terminal shell $PATH variables. Update your .cursor/mcp.json file to use full executable paths:

{
  "mcpServers": {
    "postgres": {
      "command": "/usr/local/bin/node",
      "args": [
        "/Users/username/.nvm/versions/node/v20.10.0/bin/mcp-server-postgres",
        "postgresql://localhost/mydb"
      ]
    }
  }
}

2. Inspecting Cursor MCP Logs

1. Open Cursor Settings (Cmd + , or Ctrl + ,).
2. Navigate to Features -> MCP.
3. Click View Logs next to the failing server to view full stderr stack traces.