# MCP Inspector TUI Client The Terminal User Interface (TUI) client brings the interactive exploration capabilities of the Web Client directly to your terminal. It is built using [Ink](https://github.com/vadimdemedes/ink) to provide a rich, React-like component experience in a command-line environment. ![MCP Inspector TUI Screenshot](../../docs/images/tui-screenshot.png) ## Running the TUI You can run the TUI client via `npx`: ```bash npx @modelcontextprotocol/inspector --tui node build/index.js ``` ### With Configuration Files The TUI can load all servers from an MCP catalog/config file. With no source flag it uses the default writable catalog `~/.mcp-inspector/mcp.json` (seeded empty if missing): ```bash npx @modelcontextprotocol/inspector --tui --catalog mcp.json # writable catalog (seeded empty if missing) npx @modelcontextprotocol/inspector --tui --config mcp.json # read-only session (errors if absent) ``` (It does not use `--server`; all servers in the file are available in the TUI.) ## Options ### MCP server (which server(s) to connect to) Options that specify the MCP server(s) (catalog/config file, ad-hoc command/URL, env vars, headers) are shared by the Web, CLI, and TUI and are documented in [MCP server configuration](../../docs/mcp-server-configuration.md): `--catalog` (writable catalog, seeded **empty** if missing; default `~/.mcp-inspector/mcp.json` or `MCP_CATALOG_PATH`), `--config` (read-only session, errors if absent), `-e`, `--cwd`, `--header`, `--transport`, `--server-url`, and the positional `[target...]`. `--catalog` and `--config` are mutually exclusive, and neither combines with an ad-hoc target. ### TUI-specific (OAuth for HTTP servers) The TUI supports OAuth for **SSE** and **Streamable HTTP** servers. Per-server OAuth fields in `mcp.json` (static client id/secret, scopes, enterprise-managed flag) are applied automatically when loaded from `--catalog` or `--config`. Install-wide settings (CIMD, enterprise IdP) come from **`~/.mcp-inspector/storage/client.json`** — the same file the web **Client Settings** dialog writes. You can point at a different file with `--client-config` or `MCP_CLIENT_CONFIG_PATH`. #### OAuth callback URL The TUI starts a small loopback HTTP server to receive the authorization redirect after you sign in in the browser. Defaults: | Surface | Default callback | | ------- | ------------------------------------------------------------------------------------------------- | | **Web** | `http://localhost:6274/oauth/callback` (main app server) | | **TUI** | `http://127.0.0.1:6276/oauth/callback` (dedicated runner port; avoids colliding with web on 6274) | **Why a fixed default port?** Enterprise-managed auth (EMA), CIMD, and many static OAuth apps require **pre-registered redirect URIs**. A predictable default (`http://127.0.0.1:6276/oauth/callback`) lets you register once on the IdP and reuse it across TUI sessions. Dynamic registration (DCR) can use ephemeral ports instead — see below. **Trade-off:** only **one TUI OAuth flow at a time** can listen on the default port. A second instance starting OAuth while another is in progress may fail with `EADDRINUSE`. Override the listener with `--callback-url` or `MCP_OAUTH_CALLBACK_URL` (e.g. a different fixed port per instance, or `http://127.0.0.1:0/oauth/callback` when the authorization server accepts dynamically registered redirect URIs). OAuth redirect URIs must match **exactly** what you register on the authorization server — `localhost` and `127.0.0.1` are different URIs. Register the TUI default on your OAuth app / IdP when using pre-registered (static), CIMD, or enterprise-managed clients. Override the listener with `--callback-url` or `MCP_OAUTH_CALLBACK_URL`; use `http://127.0.0.1:0/oauth/callback` for an OS-assigned ephemeral port when the authorization server registers redirect URIs dynamically (DCR). #### Flags | Option | Env | Description | | ----------------------------- | ------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `--client-config ` | `MCP_CLIENT_CONFIG_PATH` | Install-level client config (default: `~/.mcp-inspector/storage/client.json`). | | `--client-id ` | — | OAuth client ID (static client); overrides `client.json`. | | `--client-secret ` | — | OAuth client secret (confidential clients); overrides `client.json`. | | `--client-metadata-url ` | — | Client ID Metadata Document URL (CIMD); overrides `client.json`. | | `--callback-url ` | `MCP_OAUTH_CALLBACK_URL` | OAuth redirect/callback listener (default: `http://127.0.0.1:6276/oauth/callback`). Must bind a **loopback** host (`localhost` / `127.0.0.0/8` / `[::1]`); a non-loopback host hard-errors, since the listener receives the authorization code over plaintext `http`. | #### Authenticating in the TUI 1. Select an HTTP/SSE server and press **C** to connect. 2. If authorization is required, the TUI starts OAuth automatically (browser opens for sign-in). 3. After the callback completes, connect finishes without a second **C**. 4. Use the **Auth** tab to inspect OAuth state (same fields as web Connection Info) or **Clear OAuth state** (disconnects when connected). See also [EMA / enterprise-managed auth](../../specification/v2_auth_ema.md) and [OAuth smoke testing](../../specification/v2_auth_smoke_testing.md) for staging servers and verification steps. ## Features The TUI provides terminal-native tabs and panes for interacting with your MCP server: - **Resources**: Browse and read resources exposed by the server. - **Prompts**: List and test prompts. - **Tools**: View available tools and execute them with form-like inputs. - **Protocol**: View JSON-RPC request/response/notification history (matches the web Protocol monitor). - **Network**: View HTTP fetch traffic for SSE / Streamable HTTP servers (matches the web Network monitor). - **Console**: View stdio stderr from the connected server process (matches the web Console monitor). ## Navigation - Use the **Arrow Keys** (Left/Right) or **Tab** to switch between the main tabs (Resources, Tools, Prompts, etc.). - Use the **Arrow Keys** (Up/Down) to scroll through lists of items. - Press **Enter** to select an item, execute a tool, or fetch a resource. - Press **Escape** or `Ctrl+C` to exit the application. ## Development Like the other clients, the TUI self-validates from its own folder: ```bash npm run validate # format:check && lint && build && test:coverage npm test # run all tests npm run test:coverage # run tests under the per-file coverage gate ``` The repo-root `validate:tui` just delegates here. `eslint.config.js` registers `react-hooks` for the classic rules only (rules-of-hooks + exhaustive-deps); the stricter react-hooks@7 rules are not enforced on the interim component surface (#1501). Tests live in `__tests__/`. The coverage gate currently covers the TUI's non-React logic (server resolution, logger, tab metadata, and the `utils/` form/URL helpers); the Ink components and `App.tsx` are an interim exclusion in `vitest.config.ts` pending a renderer-based follow-up.