Ping Principal MCP

An MCP server that enables AI agents to request human input through native macOS dialogs. Provides a structured way for AI systems to ask clarifying questions rather than making assumptions.

Overview

This tool implements the Model Context Protocol (MCP) to facilitate human-AI interaction through system dialogs. When an AI agent encounters uncertainty, it can invoke dialog tools to gather information from the user before proceeding.

Related MCP server: Human-In-the-Loop MCP Server

Features

• Native macOS Dialogs - No files, no fuss, just clean system dialogs

• Multiple Dialog Types - Text input, multiple choice, yes/no, info, notifications

• Zero Configuration - Works out of the box with npx

• MCP Standard - Compatible with Claude Desktop, Cursor, and other MCP clients

• Timeout Handling - Dialogs don't hang forever

• macOS Only - Uses native AppleScript for authentic system integration

Installation & Usage

Quick Start

npx ping-principal-mcp

This will start the server and wait for MCP connections.

MCP Client Configuration

Claude Desktop

Add to ~/.claude_desktop_config.json:

{
  "mcpServers": {
    "ping-principal": {
      "command": "npx",
      "args": ["ping-principal-mcp"]
    }
  }
}

Cursor

Add to .cursor/mcp.json:

{
  "mcpServers": {
    "ping-principal": {
      "command": "npx", 
      "args": ["ping-principal-mcp"]
    }
  }
}

Dialog Types

Text Input

Ask open-ended questions with text responses:

await ask_human({
  type: "text",
  question: "What's the database connection string?",
  context: "Setting up production environment",
  defaultValue: "postgresql://localhost:5432/mydb"
});

Multiple Choice

Present options for the human to choose from:

await ask_human({
  type: "choice", 
  question: "Which authentication method should I implement?",
  choices: ["OAuth2", "JWT", "Session-based", "API Keys"],
  context: "Building user authentication system"
});

Yes/No Confirmation

Get confirmation before taking actions:

await ask_human({
  type: "confirm",
  question: "Should I delete the old migration files?",
  context: "Database cleanup process",
  defaultAnswer: false
});

Information Display

Show information that needs acknowledgment:

await ask_human({
  type: "info",
  question: "Migration completed successfully! 47 records updated.",
  context: "Database migration finished"
});

Notifications

Send system notifications:

await notify_human({
  message: "Build completed successfully",
  title: "Development Server",
  subtitle: "Ready for testing",
  sound: true
});

CLI Options

npx ping-principal-mcp [OPTIONS]

OPTIONS:
  -h, --help           Show help message
  -v, --version        Show version number  
  -t, --timeout SEC    Set dialog timeout in seconds (default: 300)
  -p, --port PORT      Run in HTTP mode (not yet implemented)
  -H, --host HOST      Host for HTTP mode (not yet implemented)

Examples

Development Workflow

# Start the MCP server
npx ping-principal-mcp

# Now your AI can ask questions like:
# "Should I use TypeScript strict mode for this project?"
# "What's the API endpoint for user authentication?"  
# "Should I add error handling for this edge case?"

With Custom Timeout

npx ping-principal-mcp --timeout 600  # 10 minute timeout

How It Works

1. AI gets stuck → calls ask_human() tool

2. Native dialog appears → clean macOS system dialog

3. Human responds → types answer or makes selection

4. AI continues → uses the human response to proceed

No files to manage, no polling, no complexity. Just direct human-AI communication through the OS.

Requirements

• macOS only (uses AppleScript for native dialogs)

• Node.js 18+

• MCP client (Claude Desktop, Cursor, etc.)

Dialog Timeout

Dialogs automatically timeout after 5 minutes (300 seconds) by default. You can customize this:

• Per dialog: Set timeout parameter in tool calls

• Globally: Use --timeout CLI option

• Result: Timed out dialogs return a cancellation response

Error Handling

• User cancels: Returns cancellation status instead of error

• Timeout: Graceful timeout with clear messaging

• AppleScript errors: Proper error reporting to AI

• Invalid input: Validation and sanitization

Development

From Source

git clone https://github.com/willwillems/ping-principal-mcp.git
cd ping-principal-mcp
npm install
npm run build
npm start

Project Structure

ping-principal-mcp/
├── src/
│   ├── index.ts          # CLI and main entry
│   ├── server.ts         # MCP server implementation  
│   ├── dialogs.ts        # Dialog manager & AppleScript
│   └── types.ts          # TypeScript interfaces
├── dist/                 # Compiled JavaScript
└── package.json

Building

npm run build    # Compile TypeScript
npm run dev      # Watch mode

Troubleshooting

"Permission denied" or dialogs not showing

• Check macOS privacy settings

• Grant terminal access to display dialogs

• Try running from Terminal.app vs integrated terminals

"Module not found" errors

• Make sure you're on macOS

• Check Node.js version (needs 18+)

• Try npm install in the project directory

MCP client not connecting

• Verify the configuration file syntax

• Check that the file path is correct

• Restart your MCP client after configuration changes

Contributing

Contributions welcome! Please feel free to submit issues and pull requests.

License

MIT - see LICENSE file for details.