MCP DevTools

Postman for MCP — Interactive debugger and tester for MCP Servers.

What is this?

MCP DevTools lets you connect to any MCP Server, browse its tools, and call them interactively — with an auto-generated form UI or a raw JSON editor.

Think Postman, but for the Model Context Protocol.

Features

• Connect to MCP Servers via stdio (local process) or HTTP+SSE (remote)
• Browse all available tools with their descriptions
• Auto-generated forms from JSON Schema — no manual JSON typing needed
• Monaco JSON editor with schema validation and autocomplete
• Bidirectional sync — switch between Form and JSON modes freely
• Call history with response time tracking
• Error classification — distinguish MCP protocol errors from tool errors

Quick Start

Prerequisites

• Rust (1.70+)
• Node.js 18+

Run in development

npm install
npm run tauri dev

Connect your first server

1. Click + in the left panel
2. Choose transport:
   • stdio for local servers (most common)
   • HTTP+SSE for remote servers
3. Enter the command that starts your MCP Server

Example — filesystem server:

Command: npx
Arguments: -y @modelcontextprotocol/server-filesystem /tmp

Example — test server (included):

Command: node
Arguments: /absolute/path/to/examples/test-server.js

Use the absolute path to examples/test-server.js in your local checkout.

Roadmap

• Phase 2 — Test framework: record calls as test cases, run suites in CI
• Phase 3 — Observability: call timeline visualization, P95 latency tracking

License

MIT