inspector

# MCP Inspector

A developer tool for inspecting [Model Context Protocol](https://modelcontextprotocol.io) (MCP) servers. It ships as a single package, `@modelcontextprotocol/inspector`, that provides four ways to inspect a server:

- **Web** — a Vite + React + [Mantine](https://mantine.dev) single-page app with a Node backend.
- **CLI** — a scriptable command-line client for automation, CI, and fast agent feedback loops.
- **TUI** — an interactive terminal UI built with [Ink](https://github.com/vadimdemedes/ink).
- **mcpdo** _(experimental)_ — a connection CLI: connect once, then run many commands against the named connection through an implicit local daemon. See [`clients/mcpdo`](./clients/mcpdo/README.md).

The first three run through one global `mcp-inspector` binary; `mcpdo` is a second binary in the same package:

```bash
npx @modelcontextprotocol/inspector                   # web UI (default)
npx @modelcontextprotocol/inspector --cli             # CLI
npx @modelcontextprotocol/inspector --tui             # TUI
npx -p @modelcontextprotocol/inspector mcpdo --help   # mcpdo
```

> [!WARNING]
> **The Inspector manages secrets — OAuth tokens, OAuth client secrets, and stdio `env:` values — and stores them in the OS keychain, if available, by default.** On a machine with no keychain — Linux without libsecret or a Secret Service, headless and SSH sessions, Termux, and containers with a mounted volume — they are saved to `~/.mcp-inspector/secrets.json` instead, unencrypted unless you supply a key. See [Where secrets are stored](./docs/secret-storage.md) for how to get a keychain back, encrypt the file, or keep secrets in memory only.

> **Upgrading from v1?** Read the [v1 → v2 migration guide](./docs/v1-to-v2-migration.md) — CLI flags, the new `--config` vs. `--catalog` split, the Node engine bump, and what no longer ships.

> **Repo status.** This is the **v2** line of the Inspector. Active development happens on **`v2/main`** (the develop branch — all v2 PRs target it), which is merged into **`main`** at milestone releases; `main` is the default branch and holds the latest released v2, published to the npm `latest` tag. The legacy **v1** line lives on **`v1/main`** — security fixes only, published straight from that branch to the npm `v1-latest` tag (`npx @modelcontextprotocol/inspector@v1-latest`). See [`AGENTS.md`](./AGENTS.md) for branch/board conventions.

## Quick start (development)

Requires Node `^22.23.4 || ^24.22.1 || >=26.12.1`: the patched release on each supported line.

```bash
npm install          # at the repo root; postinstall cascades into every client
npm run build        # web → cli → tui → launcher
```

For day-to-day **web** iteration, run Vite directly — fast HMR, no launcher build needed:

```bash
cd clients/web && npm run dev
```

The launcher-driven scripts run the **built** launcher, so build first:

```bash
npm run web        # prod web launcher against clients/web/dist
npm run web:dev    # web launcher in --dev mode