MCP Servers fail to connect in Cursor v0.47.5 (Client Closed status)

[snkrheadz]

Environment

• Cursor Version: 0.47.5

• Commit: 1.96.2

• Date: 53d6da1322f934a1058e7569ee0847b24879d180

• Electron: 32.2.6

• Node.js: 20.18.1

• OS: macOS

Description

All MCP servers (both custom and official) fail to connect in Cursor v0.47.5. The status remains red with “Client Closed” state, despite the servers working correctly when tested in terminal.

Affected MCP Servers

• Custom beep-sound MCP (using latest @modelcontextprotocol/sdk v1.7.0)

• Official brave-search MCP

• Official file-system MCP

Expected Behavior

• MCP servers should connect successfully

• Status should turn green when connected

Actual Behavior

• All MCP servers show “Client Closed” status

• Status remains red

• No connection is established

Steps to Reproduce

1. Configure MCP server in ~/.cursor/mcp.json:

{
  "mcpServers": {
    "some-mcp": {
      "name": "Some MCP",
      "description": "Some MCP",
      "command": "node",
      "args": [
        "/path/to/dist/mcps/some-mcp/index.js"
      ],
      "env": {
      },
      "enabled": true
    },
    "brave-search": {
      "name": "Brave Search MCP",
      "description": "Search with Brave",
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-brave-search"],
      "env": {
      },
      "enabled": true
    },
    "server-filesystem": {
      "name": "Server Filesystem MCP",
      "description": "Server Filesystem MCP",
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/path/to/server-filesystem"
      ],
      "env": {
      },
      "enabled": true
    }
  }
}

1. Start Cursor

2. Observe MCP server status (remains red with “Client Closed”)

Verification

• All MCP servers work correctly when tested directly in terminal

• Issue occurs with both custom MCPs using latest SDK and official MCPs

• Problem persists after Cursor restart

Additional Information

• The same MCPs work correctly when executed directly in terminal

• Issue appears to be independent of MCP implementation or SDK version

• Multiple different MCPs exhibit the same behavior

Possible Related Information

• Node.js version mismatch between Cursor’s internal Node.js and system Node.js

• Stdio communication issues between Cursor and MCP servers

• Potential protocol compatibility issues

Workaround Attempts

• Tested with latest @modelcontextprotocol/sdk

• Verified MCP server functionality in terminal

• Confirmed proper implementation of Stdio transport

[AntiCZ]

same problem

[AntiCZ]

Solution 1:

{
  "mcpServers": {
    "brave-search": {
      "command": "cmd",
      "args": [
        "/c",
        "npx",
        "-y",
        "@modelcontextprotocol/server-sequential-thinking"
      ],
      "env": {
        "BRAVE_API_KEY": "■■■"
      },
      "disabled": false
    }
  }
}

Solution 2:
npm i -g @modelcontextprotocol/server-sequential-thinking

{
  "mcpServers": {
    "brave-search": {
      "command": "node",
      "args": [
        "C:\\nvm4w\\nodejs\\node_modules\\@modelcontextprotocol\\server-brave-search\\dist\\index.js"
      ],
      "env": {
        "BRAVE_API_KEY": "■■■"
      },
      "disabled": false
    }
  }
}