io.github.standardbeagle/mcp-debug

Official

by standardbeagle · Go

Debug and develop MCP servers with hot-swapping, session recording, and playback testing

MCP Debug (io.github.standardbeagle/mcp-debug)

MCP Debug is a debugging and development tool for Model Context Protocol (MCP) servers. It focuses on development workflows including hot-swapping, session recording, and playback testing to support troubleshooting and repeated verification during MCP server development.

🛠️ Key Features

Debugging and development for MCP servers
Hot-swapping support
Session recording
Playback testing

🚀 Use Cases

Debug MCP server behavior while developing
Reproduce prior interactions via recorded sessions
Test and replay MCP server runs for consistency

⚡ Developer Benefits

Faster iteration with hot-swapping
Repeatable testing using session playback
Focused tooling for MCP server development and debugging

⚠️ Limitations

Only the capabilities listed in the provided description are covered: hot-swapping, recording, and playback testing; additional tooling details are not provided

Topics

debuggingdevelopmentgolanghot-swapmcpproxyrecordingtesting

README.md5 KBView on GitHub

MCP Debug

A debugging and development tool for Model Context Protocol (MCP) servers.

MCP Debug enables rapid development and testing of MCP servers with hot-swapping, session recording, and automated playback testing.

Features

Hot-Swap Development

Replace server binaries without disconnecting MCP clients
Add/remove servers dynamically during development
Tool name preservation - same interface, new implementation
Graceful disconnect/reconnect workflow for binary replacement

Session Recording & Playback

Record JSON-RPC traffic for debugging and documentation
Playback client mode - replay requests to test servers
Playback server mode - replay responses to test clients
Regression testing with recorded sessions

Development Proxy

Multi-server aggregation with tool prefixing
Real-time connection monitoring
Management API for server lifecycle control
Comprehensive logging

Installation

bash

# Using uvx (Python - recommended)
uvx mcp-debug --help

# Using npx (Node.js)
npx @standardbeagle/mcp-debug --help

# Or install globally
pip install mcp-debug              # Python
npm install -g @standardbeagle/mcp-debug  # Node.js

# Or build from source
go install github.com/standardbeagle/mcp-debug@latest

Quick Start

bash

# Start proxy with a config file
uvx mcp-debug --proxy --config config.yaml

# Or with mcp-tui for interactive testing
mcp-tui uvx mcp-debug --proxy --config config.yaml

Usage

Proxy Mode

bash

# Basic proxy
uvx mcp-debug --proxy --config config.yaml

# With recording
uvx mcp-debug --proxy --config config.yaml --record session.jsonl

# With custom log file
uvx mcp-debug --proxy --config config.yaml --log /tmp/debug.log

Management Tools:

server_add - Add a server: {name: "fs", command: "npx -y @mcp/filesystem /path"}
server_remove - Remove server completely
server_disconnect - Disconnect server (tools return errors)
server_reconnect - Reconnect with new command
server_list - Show all servers and status

Playback Modes

bash

# Replay recorded requests to test a server
uvx mcp-debug --playback-client session.jsonl | ./your-mcp-server

# Replay recorded responses to test a client
mcp-tui uvx mcp-debug --playback-server session.jsonl

Configuration

yaml

# config.yaml
servers:
  - name: "filesystem"
    prefix: "fs"
    transport: "stdio"
    command: "npx"
    args: ["-y", "@modelcontextprotocol/filesystem", "/home/user"]
    timeout: "30s"

proxy:
  healthCheckInterval: "30s"
  connectionTimeout: "10s"
  maxRetries: 3

Environment Variables

bash

MCP_LOG_FILE="/tmp/mcp-debug.log"  # Log location
MCP_DEBUG=1                         # Enable debug logging
MCP_RECORD_FILE="session.jsonl"     # Auto-record sessions
MCP_CONFIG_PATH="./config.yaml"     # Default config

Development Workflow

bash

# 1. Start with empty config
mcp-tui uvx mcp-debug --proxy --config empty-config.yaml

# 2. Add your server dynamically
server_add: {name: myserver, command: ./my-server-v1}

# 3. Test tools: myserver_read_file, myserver_process, etc.

# 4. Make changes and rebuild
go build -o my-server-v2

# 5. Hot-swap the server
server_disconnect: {name: myserver}
server_reconnect: {name: myserver, command: ./my-server-v2}

# 6. Same tools work immediately with new implementation!

CLI Commands

bash

uvx mcp-debug --help              # Show help
uvx mcp-debug --version           # Show version
uvx mcp-debug config init         # Create default config
uvx mcp-debug config show         # Show current config
uvx mcp-debug config validate     # Validate config file
uvx mcp-debug env list            # List environment variables
uvx mcp-debug env check           # Check required env vars
uvx mcp-debug tools list          # List tools with details

Project Structure

code

mcp-debug/
├── main.go              # CLI entry point
├── config/              # Configuration loading
├── client/              # MCP client implementation
├── integration/         # Proxy server and wrapper
├── discovery/           # Tool discovery
├── proxy/               # Request forwarding
├── playback/            # Recording and playback
└── test-servers/        # Example MCP servers

Building

bash

# Development build
go build -o mcp-debug .

# Production build with version info
go build -ldflags "-X main.BuildTime=$(date -u +%Y-%m-%dT%H:%M:%SZ) -X main.GitCommit=$(git rev-parse HEAD)" -o mcp-debug .

# Run tests
go test ./...

Contributing

See CONTRIBUTING.md for guidelines.

License

MIT License - see LICENSE for details.

Install

Add to VS Code Add to Cursor

claude_desktop_config.json

json

{
  "mcpServers": {
    "mcp-debug": {
      "command": "uvx",
      "args": [
        "mcp-debug"
      ]
    }
  }
}

MCP Debug (io.github.standardbeagle/mcp-debug)

🛠️ Key Features

🚀 Use Cases

⚡ Developer Benefits

⚠️ Limitations

Topics

MCP Debug

Features

Hot-Swap Development

Session Recording & Playback

Development Proxy

Installation

Quick Start

Usage

Proxy Mode

Playback Modes

Configuration

Environment Variables

Development Workflow

CLI Commands

Project Structure

Building

Contributing

License

Install

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