MCP Explorer

A terminal UI for developing, debugging, and testing MCP (Model Context Protocol) servers.

Session-based proxy debugging • Live message monitoring • Tool testing with dynamic forms • Message persistence

Features

• 🔄 Session Management - Persistent proxy sessions for debugging any MCP setup
• 🔗 Attach Mode - Connect to running proxy sessions for live debugging
• 🛠️ Tool Testing - Dynamic parameter forms generated from JSON schemas
• 🔍 Debug Mode - Live message monitoring with split-pane interface
• 💾 Message Persistence - Session history preserved across connections
• 📊 Response History - Navigate through execution history with syntax highlighting
• ⚡ Real-time - Watch MCP traffic flow in real-time with timestamps

Installation

go install github.com/kungfusheep/mcpview@latest

Or build from source:

git clone https://github.com/kungfusheep/mcpview
cd mcpview
go build -o mcpview .

Usage

Quick Start (Direct Connection)

# Interactive mode with connection prompt
mcpview

# Connect directly to an MCP server for testing
mcpview --server "python my_server.py"

# Debug mode with live message monitoring
mcpview --debug --server "npx @modelcontextprotocol/server-filesystem /"

Proxy Debugging Workflow

The most powerful way to debug MCP communication is using proxy sessions:

# 1. Start a proxy session (creates a session like "aal-swift-0625-1234")
mcpview --proxy --target "python server.py"

# 2. In another terminal, attach to debug the session
mcpview --attach                    # Shows interactive session browser
mcpview --list-sessions            # Lists all active sessions

# 3. Configure your MCP client to connect through the proxy
# Replace "python server.py" with "mcpview --proxy --target 'python server.py'"

Custom Session Management:

# Named sessions for easier identification
mcpview --proxy --target "node server.js" --session "myapi"

# Custom session storage directory
mcpview --attach --sessions-dir ./debug-sessions

Key Controls

Session List: ↑↓/jk navigate • Enter attach to session • q quit

Session Viewer: ↑↓/jk scroll messages • [/] scroll detail • Esc back to list

Tool Testing: t test tool • r resources • m messages • d debug mode • q quit

Practical Examples

Debugging Claude Desktop Integration

# 1. Start proxy for your MCP server
mcpview --proxy --target "python ~/my-mcp-server/main.py"

# 2. Update Claude Desktop config to use the proxy:
# Change: "command": "python ~/my-mcp-server/main.py"
# To: "command": "mcpview --proxy --target 'python ~/my-mcp-server/main.py'

# 3. Attach to see all Claude ↔ Server communication
mcpview --attach

Testing During Development

# Direct connection for quick tool testing
mcpview --server "python my_server.py"

# Debug mode to see protocol messages while testing
mcpview --debug --server "npx @modelcontextprotocol/server-filesystem /Users/me/docs"

Multi-Server Debugging

# Start multiple proxy sessions
mcpview --proxy --target "python db_server.py"
mcpview --proxy --target "node fs_server.js"

# Attach to debug any session
mcpview --attach    # Choose which session to inspect

What is MCP?

Model Context Protocol enables applications to provide context to LLMs in a standardized way. MCP Explorer helps you develop and debug MCP servers by providing visibility into the protocol communication.

License

Apache License 2.0 - see LICENSE for details.