MCP Explorer

A powerful TUI (Text User Interface) application for discovering, exploring, and proxying local MCP (Model Context Protocol) servers.

Features

Server Discovery & Exploration

• Automatic Discovery: Finds all configured MCP servers from Claude Code, GitHub Copilot IntelliJ, and other local configs
• FastMCP Discovery: Discovers servers from Claude Desktop, Cursor, Goose, and other supported clients via FastMCP v3
• Server Type Support: Handles stdio, HTTP streaming (StreamableHTTP), and SSE server types
• JSON5 Support: Parses both strict JSON and JSON5 (unquoted keys, comments, trailing commas)
• Config Validation: Validates configuration files with helpful error messages
• Server Overview: Lists all servers with their status, type, and capabilities at a glance
• Detailed Exploration:
  • View available tools with descriptions and parameters
  • Browse resources with URIs and metadata
  • Explore prompt templates with arguments
  • Preview prompt outputs in real-time

MCP Proxy Server (FastMCP v3)

• FastMCP v3 Proxy: Built on create_proxy() for automatic tool/resource/prompt forwarding
• Middleware Stack: Error handling, timing, ping keep-alive, response limiting, and custom logging
• Dual Transport: StreamableHTTP at /mcp (primary) and SSE at /sse (legacy)
• Rate Limiting: Optional configurable rate limiting via proxy config
• Visibility Control: Enable/disable backend servers at runtime without restart
• MCP Feature Forwarding: Elicitation, logging, and progress forwarded automatically
• Server Aggregation: Combine multiple MCP servers into a single proxy endpoint
• Port Configuration: Choose which port the proxy runs on (default: 3000)
• Granular Filtering: Select which tools, resources, and prompts to expose per server
• Persistent Config: Settings auto-save to ~/.config/mcp-explorer/proxy-config.toml
• Dynamic Status: App header shows proxy status and port in real-time
• Advanced Logging: Track all tool calls, resource reads, and prompt requests
• Log Viewer:
  • Topbar search with F3 navigation
  • Collapsible filter sidebar (Ctrl+F to toggle)
  • Expandable entries to view full parameters and responses
  • Type filters (Tools, Resources, Prompts, Errors only)
  • Search result counter and navigation buttons
  • Client connection/disconnection event logging

Interface

• Modern TUI: Built with Textual for a responsive, keyboard-driven interface
• Professional Design: Clean, muted color scheme inspired by VS Code
• Error Reporting: Clear error messages for configuration issues and connection failures

Installation

Using uv (recommended):

uv pip install -e .

Or with standard pip:

pip install -e .

Usage

Run the application:

mcp-explorer

Keyboard Shortcuts

• Navigation:

  • ↑/↓ or j/k: Navigate lists
  • Enter: Select item
  • Escape: Go back
  • Tab: Switch between tabs

• Global Actions:

  • r: Refresh server list
  • p: Open Proxy Configuration
  • l: Open Log Viewer
  • q: Quit application

• In Log Viewer:

  • F3: Next search result
  • Shift+F3: Previous search result
  • Ctrl+F: Toggle filter sidebar

• Other:

  • p: Preview prompt (when viewing a prompt)

Configuration

MCP Explorer automatically discovers servers from (in order):

1. Claude Code: ~/Library/Application Support/Claude/claude_desktop_config.json
2. GitHub Copilot IntelliJ: ~/.config/github-copilot/intellij/mcp.json
3. User MCP config: ~/.config/mcp/config.json
4. Home directory: ~/.mcp/config.json
5. Current directory: ./mcp.json or ./.mcp.json

Configuration format:

{
  "mcpServers": {
    "my-stdio-server": {
      "type": "stdio",
      "command": "uv",
      "args": ["run", "--directory", "/path/to/server", "server.py"],
      "env": {
        "API_KEY": "value"
      },
      "description": "Optional description of the server"
    },
    "my-http-server": {
      "type": "http",
      "url": "http://localhost:8080/mcp",
      "headers": {
        "Authorization": "Bearer YOUR_TOKEN"
      },
      "description": "HTTP streaming MCP server (FastMCP v3)"
    },
    "my-sse-server": {
      "type": "sse",
      "url": "http://localhost:8080/sse",
      "description": "SSE-based MCP server (legacy)"
    }
  }
}

Supported Server Types:

• stdio: Launches a local process and communicates via stdin/stdout (default)
• http: Connects to a network MCP server via StreamableHTTP (FastMCP v3 - recommended for production)
• sse: Connects to a running server via Server-Sent Events (legacy, backward compatibility)

Architecture

The application follows SOLID principles with a clean separation of concerns:

• Models: Domain entities (Server, Tool, Resource, Prompt)
• Services:
  • MCPDiscoveryService: Server discovery and initialization
  • MCPClientService: MCP protocol communication
  • MCPConfigLoader: Configuration file loading
• UI: Textual-based interface with screens, widgets, and dialogs

Development

Install development dependencies:

uv pip install -e ".[dev]"

Run tests:

pytest

Type checking:

mypy mcp_explorer

Changelog

v0.4.0 - FastMCP v3 Upgrade (Latest)

✅ FastMCP v3 create_proxy(): Replaced 300+ lines of manual proxy code with native create_proxy() (~10 lines config) ✅ Middleware Stack: ErrorHandling, Timing, Ping, ResponseLimiting, and custom ProxyLog middleware ✅ StreamableHTTP Default: Tool terminal now uses StreamableHttpTransport at /mcp instead of SSE at /sse ✅ FastMCP Discovery: New server discovery source scanning Claude Desktop, Cursor, Goose, and more ✅ Visibility Control: Runtime enable/disable of servers without proxy restart ✅ Rate Limiting: Optional configurable rate limiting via ProxyConfig ✅ MCP Feature Forwarding: Elicitation, logging, and progress forwarded automatically

v0.3.0 - HTTP Streaming Support

✅ HTTP Streaming Servers: Full support for HTTP streaming MCP servers ✅ StreamableHTTP Transport: Uses streamablehttp_client for production deployments ✅ Authentication Headers: Support for custom headers including Bearer tokens and API keys ✅ Network Accessibility: Connect to remote MCP servers over HTTP ✅ Bidirectional Streaming: Efficient real-time communication with HTTP servers ✅ Proxy Support: HTTP backend servers fully supported in the MCP proxy

v0.2.0 - SSE Client Tracking

✅ SSE Client Tracking: Log viewer displays real-time count of connected clients ✅ Connection Event Logging: Track individual client connections and disconnections with timestamps ✅ Automatic Middleware: Starlette middleware automatically tracks all SSE connections ✅ Client Statistics: View connected client count prominently in the stats bar

v0.1.0 - Initial Release

✅ Fixed ESC Navigation: ESC key now works correctly in all detail screens ✅ Fixed Resource Discovery: Server capabilities (tools, resources, prompts) now discovered without errors ✅ JSON5 Support: Handles GitHub Copilot IntelliJ configs with unquoted keys ✅ Multi-format Support: Works with both Claude Code and GitHub Copilot configs

Documentation

• QUICKSTART.md - Quick start guide with examples
• PROXY_USAGE_GUIDE.md - Complete guide to using the MCP Proxy feature (FastMCP v3)
• docs/HTTP_STREAMING_SUPPORT.md - HTTP streaming server configuration and usage guide
• docs/CONFIG_FORMATS.md - Configuration format reference