@mcpbay/apps-proxy

Local stdio proxy for MCPBay Apps - enables MCP Apps UI rendering in Claude Desktop.

Overview

MCPBay Apps provide rich interactive UIs (like network calculators, dashboards, etc.) that render directly in Claude Desktop. Because Claude Desktop only supports UI rendering for local stdio-based MCP servers, this proxy bridges the gap by connecting to your remote MCPBay Apps endpoint while running locally.

Requirements

• Node.js 18 or higher
• MCPBay account with Professional tier or higher
• Your MCPBay API key (found in the MCPBay Dashboard)

Installation

npm install -g @mcpbay/apps-proxy

Configuration

Add the proxy to your Claude Desktop configuration file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "mcpbay-apps": {
      "command": "mcpbay-apps-proxy",
      "env": {
        "MCPBAY_APPS_URL": "https://YOUR-SERVICE.mcpbay.ai/apps",
        "MCPBAY_API_KEY": "your-api-key-from-dashboard"
      }
    }
  }
}

Replace:

• YOUR-SERVICE with your MCPBay service slug (e.g., myserver)
• your-api-key-from-dashboard with your API key from the MCPBay Dashboard

Environment Variables

| Variable | Required | Description | |----------|----------|-------------| | MCPBAY_APPS_URL | Yes | Your MCPBay Apps endpoint URL | | MCPBAY_API_KEY | Yes | Your MCPBay API key for authentication |

Usage

After configuring Claude Desktop, restart the application. The proxy will automatically connect to your MCPBay Apps endpoint.

To test manually:

MCPBAY_APPS_URL=https://myserver.mcpbay.ai/apps \
MCPBAY_API_KEY=your-api-key \
mcpbay-apps-proxy

How It Works

1. Claude Desktop launches the proxy as a local stdio MCP server
2. The proxy connects to your remote MCPBay Apps endpoint
3. Tool calls and resource requests are forwarded with authentication
4. UI metadata is passed through, enabling rich interactive experiences

Troubleshooting

"Authentication failed: Invalid API key"

• Verify your API key is correct in the MCPBay Dashboard
• Ensure there are no extra spaces or characters in the config

"Access denied: MCP Apps requires Professional tier"

• MCP Apps is a Professional tier feature
• Upgrade your subscription at mcpbay.ai/dashboard

Proxy won't start

• Ensure Node.js 18+ is installed: node --version
• Check that environment variables are set correctly
• Look for error messages in Claude Desktop logs

Support

• Documentation: https://docs.mcpbay.ai
• Dashboard: https://mcpbay.ai/dashboard
• Issues: https://github.com/mcpbay/mcpbay-apps-proxy/issues

License

MIT