MCP Inspector is the officially maintained MCP protocol testing tool, offering Web, CLI, and TUI interfaces to inspect any MCP server's tools, resources, prompts, and low-level protocol traffic — well suited to protocol development and debugging, but it is not itself a business-facing MCP server meant to be called by end users or AI clients.
MCP Inspector is a developer tool maintained in the official Model Context Protocol repository (modelcontextprotocol/inspector) for inspecting and debugging MCP servers — it is a client-side testing tool, not an MCP server that exposes tools to AI clients. It ships as a single npm package, @modelcontextprotocol/inspector, providing three ways to inspect a server through one mcp-inspector binary: a Web UI (Vite + React + Mantine, default), a scriptable CLI for automation and CI, and an interactive terminal UI (TUI) built with Ink. All three share connection logic, state stores, and OAuth handling via the internal @inspector/core package. The project's current line is v2 (branch v2/main); main holds the legacy v1 implementation in bug-fix-only mode. The repo also bundles composable test MCP servers and ready-made showcase configs demonstrating pagination, resource subscriptions, tasks, logging, and multi-round-trip (MRTR) elicitation across both legacy and modern protocol eras.
Run it without installing: npx @modelcontextprotocol/inspector opens the Web UI by default; add --cli for the command-line client or --tui for the terminal UI. To develop from source, install Node >=22.19.0, run npm install at the repo root (cascades into every client), then npm run build, or run cd clients/web && npm run dev for fast Web HMR iteration. An official Docker image is also published: docker run --rm -p 6274:6274 ghcr.io/modelcontextprotocol/inspector.