Pling MCP Proxy

HTTP-to-stdio proxy for remote MCP servers. Use any HTTP MCP endpoint from Claude Desktop (stdio).

Package

• Name: @plingcast/mcp-proxy
• Registry: npm
• Use case: Connect Claude Desktop to HTTP MCP servers via stdio

Usage

Environment variables

| Variable | Required | Description | | ------------- | -------- | ---------------------------------- | | MCP_URL | Yes | MCP server base URL | | MCP_API_KEY | No | API key when the server needs auth |

Claude Desktop config (with API key)

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "my-mcp": {
      "command": "npx",
      "args": ["-y", "@plingcast/mcp-proxy"],
      "env": {
        "MCP_URL": "https://your-mcp-server.example.com/mcp",
        "MCP_API_KEY": "your_api_key"
      }
    }
  }
}

Claude Desktop config (no auth)

{
  "mcpServers": {
    "my-mcp": {
      "command": "npx",
      "args": ["-y", "@plingcast/mcp-proxy"],
      "env": {
        "MCP_URL": "https://your-mcp-server.example.com/mcp"
      }
    }
  }
}

Omit MCP_API_KEY when the MCP server does not require authentication.

Note: For Pling MCP usage, obtain MCP_URL and MCP_API_KEY from your administrator. The stdio proxy runs automatically when Claude Desktop starts; add it to your config file only—no separate process or manual run is required.

Development

Build

npm install
npm run build

Local run

MCP_URL=https://your-server.example.com/mcp \
MCP_API_KEY=your_api_key \
node dist/index.js

Project layout

pling-mcp-proxy/
├── index.ts       # HTTP → stdio proxy
├── package.json
├── tsconfig.json
└── README.md

Data flow

Claude Desktop (stdio)
    ↓ JSON-RPC via stdin/stdout
proxy (npx @plingcast/mcp-proxy)
    ↓ HTTP (Api-Key header when MCP_API_KEY is set)
MCP Server

Troubleshooting

npx fails or "You must supply a command"

• Node.js >= 18.0.0 required. Check with npx --version.
• Some clients (e.g. Claude Desktop) may run npx with a different Node from PATH, which can cause errors.

"Cannot find module 'node:path'" or npx runs with wrong Node

• The app may be invoking npx with an older Node (e.g. from PATH). Use node + full path instead of npx so the same Node runs the proxy.

  1. Install globally: npm install -g @plingcast/mcp-proxy
  2. Get the script path:

     echo "$(npm root -g)/@plingcast/mcp-proxy/dist/index.js"

  3. In your config, set command to your Node binary and args to the path from step 2 (as a single-element array). Example:

     "command": "/path/to/node/v24.6.0/bin/node",
     "args": ["/path/to/node/v24.6.0/lib/node_modules/@plingcast/mcp-proxy/dist/index.js"]

     Replace /path/to/node/... with the output of which node or your nvm path (e.g. ~/.nvm/versions/node/v24.6.0/bin/node).

401 Unauthorized

• Verify MCP_API_KEY and that the key is not expired.

Connection errors

• Confirm MCP_URL is correct and reachable from your network.