Reloaderoo

A local MCP server for developers that mirrors your in-development MCP server, allowing seamless restarts and tool updates so you can build, test, and iterate on your MCP server within the same AI session without interruption.

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reloaderoo

npm version License: MIT Node.js

Hot-reload your MCP servers without restarting your AI coding assistant

A transparent development proxy for the Model Context Protocol (MCP) that enables seamless hot-reloading of MCP servers during development. Works excellently with VSCode MCP, well with Claude Code, and supports other MCP-enabled clients.

🎯 Why reloaderoo?

When developing MCP servers, you typically need to restart your entire AI coding session every time you make changes to your server code. This breaks your development flow and loses context.

reloaderoo solves this by:

  • 🔄 Hot-reloading your MCP server without disconnecting the client
  • 🔧 Preserving session state between server restarts
  • 🛠️ Adding a restart_server tool that your AI agent can call
  • 🌊 Transparent forwarding of all MCP protocol messages
  • 📡 Full protocol support (tools, resources, prompts, completion, ping)

🚀 Quick Start

Installation

# Install globally for easy access
npm install -g reloaderoo

# Or install locally in your project
npm install --save-dev reloaderoo

Basic Usage

Instead of connecting your AI client directly to your MCP server:

# ❌ Traditional approach (requires client restart on changes)
# Client connects to: node my-mcp-server.js

Connect through reloaderoo:

# ✅ With reloaderoo (hot-reload without client restart)
reloaderoo -- node my-mcp-server.js

Now your client connects to the proxy, and the proxy manages your server's lifecycle!

🔌 Client Compatibility

MCP ClientStatusToolsPromptsResourcesHot-ReloadNotes
VSCode✅ Excellent✅ Full✅ Full✅ Full✅ Auto-detectDetects tool addition/removal + updates
Claude Code✅ Good✅ Full✅ Full❌ Not supported⚠️ Manual refreshTool updates work, no auto-detection
Cursor✅ Excellent✅ Full❓ Untested❓ Untested✅ Auto-detectDetects tool addition/removal + updates
Windsurf✅ Good✅ Full❓ Untested❓ Untested⚠️ Manual refreshTool updates work, no auto-detection

🎯 Recommended Clients

Best Experience: VSCode & Cursor - Full protocol support with automatic capability detection
Good Experience: Claude Code & Windsurf - Works well, may need manual refresh for new tools

🛠️ Development Workflow

1. Start Development Session

Configure your AI client (VSCode recommended, Claude Code also works well) to connect to:

reloaderoo -- node my-mcp-server.js --log-level debug

2. Develop Your MCP Server

Work on your server code as usual:

// my-mcp-server.js
export const server = new Server({
  name: "my-awesome-server",
  version: "1.0.0"
});

// Add new tools, modify existing ones, etc.
server.addTool("new_feature", /* ... */);

3. Test Changes Instantly

Ask your AI agent to restart the server:

"Please restart the MCP server to load my changes"

The agent will call the restart_server tool automatically. Your new capabilities are immediately available!

4. Continue Development

Your AI session continues with the updated server capabilities. No connection loss, no context reset.

📋 Command Line Options

reloaderoo [options] -- <command> [args...]

Options:
  -w, --working-dir <directory>    Working directory for the server process
  -l, --log-level <level>          Log level (debug, info, warning, error)
  -m, --max-restarts <number>      Maximum restart attempts (default: 3)
  -d, --restart-delay <ms>         Delay between restarts (default: 1000ms)
  -t, --restart-timeout <ms>       Restart timeout (default: 30000ms)
  --no-auto-restart               Disable automatic restart on crashes
  --dry-run                       Validate configuration without starting
  
Commands:
  info                            Show system information and diagnostics

🏗️ How It Works

graph LR
    A[AI Client] -->|MCP Protocol| B[reloaderoo]
    B -->|Forwards Messages| C[Your MCP Server]
    B -->|Manages Lifecycle| C
    B -->|Adds restart_server Tool| A
    
    style A fill:#e1f5fe
    style B fill:#f3e5f5  
    style C fill:#e8f5e8

The Magic Behind the Scenes:

  1. Transparent Forwarding: All MCP messages pass through seamlessly
  2. Capability Augmentation: Adds restart_server tool to your server's capabilities
  3. Process Management: Spawns, monitors, and restarts your server process
  4. Session Persistence: Client connection remains active during server restarts
  5. Protocol Compliance: Full MCP v2025-03-26 support with intelligent fallbacks

🔧 Configuration

Environment Variables

# Configure via environment variables
export MCPDEV_PROXY_LOG_LEVEL=debug
export MCPDEV_PROXY_RESTART_LIMIT=5
export MCPDEV_PROXY_AUTO_RESTART=true
export MCPDEV_PROXY_TIMEOUT=30000

Configuration File Support

// reloaderoo.config.js
export default {
  childCommand: "node",
  childArgs: ["server.js"],
  logLevel: "debug",
  maxRestarts: 5,
  autoRestart: true
};

🎨 Integration Examples

Claude Code Integration

Add to your project's claude_desktop_config.json:

{
  "mcpServers": {
    "my-dev-server": {
      "command": "reloaderoo",
      "args": ["--log-level", "info", "--", "node", "my-server.js"]
    }
  }
}

Package.json Scripts

{
  "scripts": {
    "dev": "reloaderoo -- npm run server:dev",
    "mcp:proxy": "reloaderoo -- node dist/server.js",
    "mcp:debug": "reloaderoo --log-level debug -- node server.js"
  }
}

🚨 Troubleshooting

Client Compatibility Issues

Universal configuration (all clients):

{
  "mcpServers": {
    "MyServer": {
      "command": "node",
      "args": [
        "/path/to/reloaderoo.js",
        "--working-dir",
        "/path/to/accessible/directory",
        "--",
        "node",
        "/path/to/my-server.js"
      ]
    }
  }
}

Claude Code not detecting new tools:

  • Tools will work after restart, but auto-detection may not occur
  • Manually restart conversation or refresh client to see new tools
  • Existing tool updates are detected automatically

VSCode best experience:

  • Automatic tool detection and updates
  • Full protocol support (tools, prompts, resources)
  • Real-time capability changes

Common Issues

Server won't start:

# Check if your server runs independently first
node my-server.js

# Then try with dry-run to validate configuration
reloaderoo -- node my-server.js --dry-run

Connection problems:

# Enable debug logging
reloaderoo --log-level debug -- node my-server.js

# Check system info
reloaderoo info --verbose

Restart failures:

# Increase restart timeout
reloaderoo -- node my-server.js --restart-timeout 60000

# Check restart limits  
reloaderoo -- node my-server.js --max-restarts 5

Debug Mode

# Get detailed information about what's happening
reloaderoo -- node my-server.js --debug

# View system diagnostics
reloaderoo info --verbose

📚 API Reference

The restart_server Tool

Your AI agent can call this tool to restart your server:

interface RestartServerParams {
  force?: boolean;  // Force restart even if server appears healthy
  config?: {
    environment?: Record<string, string>;    // Update environment variables
    childArgs?: string[];                    // Update command arguments  
    workingDirectory?: string;               // Update working directory
  };
}

Example usage in conversation:

"Please restart the MCP server to load my latest changes"
"Force restart the server even if it seems to be working"  
"Restart the server with debug logging enabled"

🔧 Client-Specific Setup

VSCode (Recommended)

// settings.json or workspace config
{
  "mcpServers": {
    "my-dev-server": {
      "command": "reloaderoo",
      "args": ["--", "node", "my-server.js"]
    }
  }
}

✅ Auto-detection: New tools appear automatically after restart
✅ Full protocol: Tools, prompts, resources all supported
✅ Real-time updates: Changes to existing tools detected immediately

Claude Code

// claude_desktop_config.json  
{
  "mcpServers": {
    "my-dev-server": {
      "command": "reloaderoo",
      "args": ["--", "node", "my-server.js"]
    }
  }
}

✅ Tools & Prompts: Full support for tools and prompts
⚠️ Manual refresh: May need to restart conversation for new tools
❌ Resources: Not supported by Claude Code (client limitation)

Cursor & Windsurf (Issues)

⚠️ Known Issues: Both clients experiencing identical server startup errors
🔍 Investigation: Compatibility problems under investigation (may be shared architecture)
📋 Workaround: Use VSCode or Claude Code for now

🤝 Contributing

We welcome contributions! Please see CONTRIBUTING.md for guidelines.

Development Setup

git clone https://github.com/your-org/reloaderoo.git
cd reloaderoo
npm install
npm run build
npm test

Running Tests

npm run test          # Unit tests
npm run test:e2e      # End-to-end tests with MCP Inspector
npm run test:coverage # Test coverage report

📄 License

MIT License - see LICENSE file for details.

🔗 Related Projects

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