MCP server not showing in Cursor (or showing a red dot)

The error

Why it happens

Cursor only reads ~/.cursor/mcp.json (global) or .cursor/mcp.json in the project root. A wrong file location, a typo in the mcpServers key, invalid JSON, or a command that crashes on start all leave the server missing or red.

How to fix it

1. Put the config in the right place
   Global: ~/.cursor/mcp.json. Per project: <project>/.cursor/mcp.json. The top-level key must be mcpServers.

   {
     "mcpServers": {
       "playwright": {
         "command": "npx",
         "args": ["-y", "@playwright/mcp@latest"]
       }
     }
   }

2. Run the command yourself
   Copy the exact command and args into a terminal (e.g. npx -y @playwright/mcp@latest). If it errors there, it will error in Cursor too.
3. Check the MCP log
   Open the Output panel (Cmd/Ctrl+Shift+U) and choose MCP Logs from the dropdown to see the real error.
4. Toggle and reload
   Open Customize in the sidebar, find the server under MCP, and toggle it off and on. You can also run "Developer: Reload Window".

Related servers

Sources

• https://cursor.com/docs/context/mcp
• https://modelcontextprotocol.io/docs/tools/debugging