OneMCP - MCP Server Aggregator

OneMCP is a native macOS application that aggregates multiple Model Context Protocol (MCP) servers into a unified interface. It provides a seamless way to manage and interact with multiple MCP servers through a single endpoint, complete with a modern SwiftUI interface and system tray integration.

🚀 Features

Core Functionality

• MCP Server Aggregation: Connect and manage multiple upstream MCP servers through a unified interface
• Multi-Protocol Support: Supports Standard I/O, Server-Sent Events (SSE), and HTTP transport protocols
• Unified HTTP Endpoint: Exposes all connected servers through a single HTTP interface for downstream clients
• Real-time Status Monitoring: Live monitoring of server connections, capabilities, and performance metrics

User Interface

• Native macOS App: Built with SwiftUI for a modern, native macOS experience
• System Tray Integration: Convenient menu bar access with status indicators
• Multi-Tab Interface: Organized views for Overview, Servers, Capabilities, and Logs
• Settings Management: Comprehensive configuration through a dedicated settings panel

Advanced Features

• Capability Prefixing: Automatically prefixes capabilities from different servers to avoid naming conflicts
• Performance Monitoring: Built-in performance tracking with alerts and metrics
• Retry Logic: Configurable retry mechanisms for unreliable server connections
• CORS Support: Configurable CORS settings for web client integration
• Notifications: System notifications for server status changes and errors

📋 Requirements

• macOS 13.0 or later
• Swift 6.0+
• Xcode 15.0+ (for development)

🛠 Installation

Pre-built Binary

Download the latest release from the Releases page.

Building from Source

1. Clone the repository:

   git clone https://github.com/your-repo/onemcp.git
   cd onemcp
   

2. Build the application:

   make app
   

3. Install to Applications folder:

   cp -r OneMCP.app /Applications/
   

Development Build

For development, you can run the app directly:

make run

⚙️ Configuration

OneMCP stores its configuration in ~/Library/Application Support/OneMCP/config.json. The application provides a graphical interface for configuration, but you can also edit the JSON directly.

Server Configuration

OneMCP supports three types of upstream servers:

1. Standard I/O Servers

{
  "id": "uuid-here",
  "name": "My StdIO Server",
  "type": "stdio",
  "enabled": true,
  "config": {
    "stdio": {
      "command": "/path/to/server",
      "arguments": ["--arg1", "value1"],
      "environment": {
        "KEY": "value"
      },
      "workingDirectory": "/path/to/working/dir"
    }
  }
}

2. Server-Sent Events (SSE) Servers

{
  "id": "uuid-here",
  "name": "My SSE Server",
  "type": "sse",
  "enabled": true,
  "config": {
    "sse": {
      "url": "http://localhost:3001/sse",
      "headers": {
        "Authorization": "Bearer token"
      }
    }
  }
}

3. HTTP Servers

{
  "id": "uuid-here",
  "name": "My HTTP Server",
  "type": "streamable-http",
  "enabled": true,
  "config": {
    "streamableHttp": {
      "url": "http://localhost:3002",
      "headers": {
        "Authorization": "Bearer token"
      }
    }
  }
}

Application Settings

{
  "server": {
    "port": 3000,
    "host": "localhost",
    "enableCors": true
  },
  "ui": {
    "startMinimized": false,
    "showInDock": true,
    "enableNotifications": true,
    "theme": "system"
  },
  "logging": {
    "level": "info",
    "enableFileLogging": true,
    "maxLogSize": 10000000
  }
}

🔧 Usage

Starting the Application

1. Launch OneMCP from the Applications folder or system tray
2. The application will start the aggregation server on the configured port (default: 3000)
3. Configure your upstream MCP servers through the Settings panel
4. Monitor server status through the Overview tab

Connecting Downstream Clients

Once OneMCP is running, downstream clients can connect to the aggregated endpoint:

http://localhost:3000

All capabilities from connected upstream servers will be available through this single endpoint, with automatic prefixing to avoid naming conflicts.

Menu Bar Features

• Server Status: Green/red indicator showing overall server status
• Quick Actions: Access to main window and settings
• Notifications: Real-time alerts for server status changes

🏗 Architecture

Core Components

• MCPAggregationService: Main service orchestrating server connections and capability aggregation
• UpstreamManager: Manages connections to upstream MCP servers
• HTTPServerTransport: HTTP server implementation for downstream clients
• AppState: Central state management using SwiftUI's ObservableObject
• ConfigManager: Configuration persistence and management

Transport Layer

OneMCP supports multiple transport protocols:

• SubprocessStdioTransport: For command-line MCP servers
• LegacySSETransport: For Server-Sent Events connections
• HTTPServerTransport: For HTTP-based MCP servers

Capability Aggregation

• Capabilities from different servers are prefixed with server names to avoid conflicts
• Example: server1_tool_name, server2_tool_name
• Original capability names are preserved in metadata for reference

🧪 Testing

Run the test suite:

make test

📊 Performance Monitoring

OneMCP includes built-in performance monitoring:

• Connection Metrics: Active connections, total connections, error rates
• Request Metrics: Response times, success/failure rates
• Resource Usage: Memory usage tracking
• Alerts: Configurable performance alerts

🛡 Security

• Localhost Binding: Default configuration binds to localhost for security
• CORS Configuration: Configurable CORS settings for web client integration
• Process Isolation: Upstream servers run in separate processes
• Error Isolation: Failures in one upstream server don't affect others

🐛 Troubleshooting

Common Issues

1. Port Already in Use: OneMCP will automatically find an alternative port and notify you
2. Server Connection Failures: Check server configuration and logs in the Logs tab
3. Performance Issues: Monitor the Performance tab for bottlenecks

Logs

View detailed logs through:

• The Logs tab in the main interface
• Console.app (search for "OneMCP")
• Log files in ~/Library/Application Support/OneMCP/

🤝 Contributing

1. Fork the repository
2. Create a feature branch: git checkout -b feature/amazing-feature
3. Commit your changes: git commit -m 'Add amazing feature'
4. Push to the branch: git push origin feature/amazing-feature
5. Open a Pull Request

📝 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• Built using the Swift MCP SDK
• Uses Swift Service Lifecycle for service management
• Logging provided by Swift Log

📞 Support

For support, please:

• Check the Issues page
• Create a new issue with detailed information
• Include relevant logs and configuration details

OneMCP - Simplifying MCP server management on macOS