3c1bbbcb5f
The hint under a form with unfilled required fields reads "you have not competed yet". The string is upstream's, hardcoded in `ink-form/lib/SubmitButton.js` with no prop to override it, and `ink-form` was last published in 2024 — but it renders in the Inspector's tool, prompt, and resource test forms, so it is ours to fix in practice. Bundling `ink-form` (previous commit) is what makes it patchable: an esbuild `onLoad` hook rewrites the label as the file enters the bundle. The hook throws when the string is absent rather than passing the source through, so an `ink-form` upgrade cannot silently retire the patch or leave it aimed at a string that no longer exists — the tests drive it against the real dependency source for the same reason. Reported upstream as lukasbach/ink-form#14. Closes #1952 Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01WLYmVPVLdeYpE6aMTUsCks
156 lines
11 KiB
Markdown
156 lines
11 KiB
Markdown
# MCP Inspector TUI Client
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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.
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## Running the TUI
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You can run the TUI client via `npx`:
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```bash
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npx @modelcontextprotocol/inspector --tui node build/index.js
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```
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### With Configuration Files
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The TUI can load all servers from an MCP catalog/config file. With no source
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flag it uses the default writable catalog `~/.mcp-inspector/mcp.json` (seeded
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empty if missing):
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```bash
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npx @modelcontextprotocol/inspector --tui --catalog mcp.json # writable catalog (seeded empty if missing)
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npx @modelcontextprotocol/inspector --tui --config mcp.json # read-only session (errors if absent)
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```
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(It does not use `--server`; all servers in the file are available in the TUI.)
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## Options
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### MCP server (which server(s) to connect to)
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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.
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### TUI-specific (OAuth for HTTP servers)
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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`.
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#### OAuth callback URL
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The TUI starts a small loopback HTTP server to receive the authorization redirect after you sign in in the browser. Defaults:
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| Surface | Default callback |
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| ------- | ------------------------------------------------------------------------------------------------- |
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| **Web** | `http://localhost:6274/oauth/callback` (main app server) |
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| **TUI** | `http://127.0.0.1:6276/oauth/callback` (dedicated runner port; avoids colliding with web on 6274) |
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**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.
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**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).
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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).
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#### Flags
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| Option | Env | Description |
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| ----------------------------- | ------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
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| `--client-config <path>` | `MCP_CLIENT_CONFIG_PATH` | Install-level client config (default: `~/.mcp-inspector/storage/client.json`). |
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| `--client-id <id>` | — | OAuth client ID (static client); overrides `client.json`. |
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| `--client-secret <secret>` | — | OAuth client secret (confidential clients); overrides `client.json`. |
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| `--client-metadata-url <url>` | — | Client ID Metadata Document URL (CIMD); overrides `client.json`. |
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| `--callback-url <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`. |
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#### Authenticating in the TUI
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1. Select an HTTP/SSE server and press **C** to connect.
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2. If authorization is required, the TUI starts OAuth automatically (browser opens for sign-in).
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3. After the callback completes, connect finishes without a second **C**.
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4. Use the **Auth** tab to inspect OAuth state (same fields as web Connection Info) or **Clear OAuth state** (disconnects when connected).
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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.
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## Features
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The TUI provides terminal-native tabs and panes for interacting with your MCP server:
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- **Resources**: Browse and read resources exposed by the server.
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- **Prompts**: List and test prompts.
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- **Tools**: View available tools and execute them with form-like inputs.
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- **Protocol**: View JSON-RPC request/response/notification history (matches the web Protocol monitor).
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- **Network**: View HTTP fetch traffic for SSE / Streamable HTTP servers (matches the web Network monitor).
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- **Console**: View stdio stderr from the connected server process (matches the web Console monitor).
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## Navigation
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- Use the **Arrow Keys** (Left/Right) or **Tab** to switch between the main tabs (Resources, Tools, Prompts, etc.).
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- Use the **Arrow Keys** (Up/Down) to scroll through lists of items.
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- Press **Enter** to select an item, execute a tool, or fetch a resource.
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- Press **Escape** or `Ctrl+C` to exit the application.
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## Development
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Like the other clients, the TUI self-validates from its own folder:
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```bash
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npm run validate # format:check && lint && build && test:coverage
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npm test # run all tests
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npm run test:coverage # run tests under the per-file coverage gate
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```
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The repo-root `validate:tui` just delegates here. `eslint.config.js` registers
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`react-hooks` for the classic rules only (rules-of-hooks + exhaustive-deps); the
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stricter react-hooks@7 rules are not enforced on the interim component surface
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(#1501).
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Tests live in `__tests__/`. The coverage gate currently covers the TUI's
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non-React logic (server resolution, logger, tab metadata, and the `utils/`
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form/URL helpers); the Ink components and `App.tsx` are an interim exclusion in
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`vitest.config.ts` pending a renderer-based follow-up.
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### Bundling: React-rendering dependencies must be inlined (#1952)
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`tsup.config.ts` splits the TUI's dependencies into bundled (`noExternal`) and
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externalized (`external`). For anything that **renders React components**, that
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choice decides which React instance it gets at runtime, and getting it wrong
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crashes the TUI in a way nothing in this repo can see.
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An external package's `import "react"` resolves from wherever npm placed **that
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package** — and npm places it next to a React satisfying its own peer range.
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`ink-form` and `ink-scroll-view` both accept `react: ">=18"`, so a project that
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installs the Inspector alongside its own React 18 satisfies them: they hoist to
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that project's root while the Inspector's React 19 nests underneath. The bundle
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then renders through React 19 while those two call hooks on React 18, whose
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dispatcher is null — so opening a tool test form (or any scroll view) dies with
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`TypeError: Cannot read properties of null (reading 'useState')`.
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Bundling them removes npm from the decision: their `import "react"` is emitted
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into `build/index.js`, so it resolves from the build directory exactly like the
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bundle's own. It also pins their transitive deps to what *this* install
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resolved — notably `ink-select-input@6` via the `overrides` entry, since npm
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ignores a dependency's `overrides` and a consumer install would otherwise pull
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the React-18-era v5 that `ink-form` asks for.
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`ink` itself stays external: it can't be bundled (its CJS `signal-exit@3`
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dependency fails ESM interop with `Dynamic require of "assert" is not
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supported`), and it doesn't need to be — its `react` peer is `">=19"`, which
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keeps npm from hoisting it next to a React the Inspector couldn't also use.
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`__tests__/tsupConfig.test.ts` enforces this: every dependency declaring a
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`react` peer must be in `noExternal` unless it is listed as external by design.
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Add a React-rendering dependency, and that test tells you to bundle it.
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### The `ink-form` label patch
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Bundling `ink-form` also makes it patchable, which one label needs: the hint
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under an incomplete form reads "you have not **competed** yet". It is upstream's
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string, hardcoded in `ink-form/lib/SubmitButton.js` with no prop to override,
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and `ink-form` was last published in 2024 — so `tsup.config.ts` corrects it with
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an esbuild `onLoad` hook as the file enters the bundle. It is reported upstream
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as [lukasbach/ink-form#14](https://github.com/lukasbach/ink-form/issues/14); if
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a release ever carries the fix, drop the patch.
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The hook **throws** when the string isn't found rather than passing the source
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through. A silent no-op would let an `ink-form` upgrade retire the patch without
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anyone noticing it had stopped applying — or leave a patch aimed at a string
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that no longer exists. If the build fails there, check whether upstream fixed
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the typo and delete the patch instead of re-targeting it.
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