mcpeek - MCP Server Inspector

A Rust CLI tool for inspecting and interacting with Model Context Protocol (MCP) servers.

Features

• Interactive Terminal User Interface:

  • Real-time exploration of MCP servers
  • Tab-based navigation between different capabilities
  • Live log viewer for server output

• Full MCP Support:

  • List and inspect tools
  • Interactive tool execution with form-based parameter input
  • Browse prompts and their arguments
  • View available resources
  • Display server capabilities and information
  • Execute tool calls with custom parameters

Installation

cargo build --release

The binary will be available at target/release/mcpeek.

Usage

Launch the interactive terminal interface to explore an MCP server:

mcpeek <server-command> [server-args...]

Examples:

# Connect to a Node.js MCP server
mcpeek node /path/to/server.js

# Connect to a Python MCP server
mcpeek python -m my_mcp_server

# With uvx
mcpeek uvx mcp-server-git

TUI Controls:

• Tab / ←/→: Switch between tabs (Tools, Prompts, Resources, Server Info, Logs)
• ↑/↓: Navigate items in lists (or scroll logs in Logs tab)
• Enter: View detailed information about selected item
• C: Call/execute the selected tool (in Tools tab)
• E: Jump to end of logs (in Logs tab)
• R: Refresh current tab
• Esc: Close detail view or cancel tool call input
• Q: Quit application

Tool Calling (in Tools tab):

When you press C on a selected tool:

• An input form appears showing all tool parameters
• Navigate between fields using Tab / Shift+Tab
• Type values directly into each field
• Required fields are marked as "(required)"
• Press Enter to execute the tool call
• Press Esc to cancel
• Results are displayed in the detail view

Tabs:

• Tools: Browse and inspect available tools, execute tool calls with interactive parameter input
• Prompts: View prompts and their arguments
• Resources: List available resources
• Server Info: Display server capabilities and version information
• Logs: View server stderr output in real-time (automatically captures server logs)

Debug Mode

Enable debug logging to stderr:

mcpeek --debug node server.js

Architecture

src/
├── main.rs           # CLI entry point and TUI event loop
├── mcp/
│   ├── mod.rs        # Module exports
│   ├── client.rs     # MCP client with JSON-RPC over stdio
│   └── protocol.rs   # MCP protocol types and messages
└── tui/
    ├── mod.rs        # TUI module exports
    ├── app.rs        # Application state management
    └── ui.rs         # UI rendering logic

Key Components

MCP Client (mcp/client.rs):

• Manages subprocess lifecycle
• Handles JSON-RPC communication over stdio
• Implements async message passing with tokio
• Provides high-level methods for MCP operations

Protocol Types (mcp/protocol.rs):

• Comprehensive type definitions for MCP protocol
• JSON serialization/deserialization with serde
• Supports initialize, tools, prompts, and resources capabilities

TUI (tui/):

• Built with ratatui for rich terminal interfaces
• Tab-based navigation between different MCP capabilities
• Detail views for in-depth item inspection
• Real-time error handling and loading states
• Live log viewer that captures server stderr output

MCP Protocol Support

This tool implements the MCP protocol version 2024-11-05 and supports:

• ✅ Server initialization and capability negotiation
• ✅ Tools (list, call)
• ✅ Prompts (list, get)
• ✅ Resources (list, read)
• ✅ Server information display

Requirements

• Rust 2021 edition or later
• An MCP-compatible server to connect to

Development

Run in development mode:

# Run the TUI
cargo run -- <server-command> [args...]

# With debug logging
cargo run -- --debug <server-command> [args...]

License

MIT License - see LICENSE for details.

Contributing

Contributions are welcome! Areas for enhancement:

• Support for additional MCP protocol features
• Enhanced error recovery
• Resource subscription support
• Sampling capabilities
• Configuration file support
• Advanced input types (arrays, nested objects) in tool call forms

Made with ❤️. Fueled by ☕️ and 🤖.