Command-Line MCP Server

A remote Model Context Protocol server that exposes a single tool, run_command, allowing Claude (via the Claude Desktop Connectors feature) to execute shell commands on the machine running this server.

The server implements OAuth 2.1 (Dynamic Client Registration + PKCE) because Claude Desktop connectors require an OAuth handshake — a connector with no auth server is rejected at sign-in. This server auto-approves authorization (no user prompt), which is fine for a personal, tunnel-exposed server.

⚠️ Security warning: Anyone who can reach this server and complete the (automatic) OAuth flow can run arbitrary commands as the user running it. Only expose it through a private tunnel (cloudflared / ngrok) and never on a public network.

How it works

• Transport: Streamable HTTP (the transport Claude Desktop connectors require).

• Stateless: every request spins up a fresh server/transport instance (no session store needed).

• Endpoint: POST /mcp

• Health check: GET /health

Tools

run_command

Execute a shell command. On Windows the default shell is cmd.exe (use dir, cd, not ls/pwd) unless you pass shell: "powershell".

get_info

Returns OS, architecture, default shell (cmd.exe on Windows), and current working directory — call once so the client knows which shell to use.

read_file

Read a text file (optional offset/limit line range). path is absolute or relative to cwd.

list_files

List a directory. recursive: true walks the tree (depth-limited to 4).

edit_file

Exact string replace — the preferred way to edit code (no shell escaping needed). path, old_text, new_text, optional replace_all. old_text must be unique unless replace_all is set. Returns a short diff.

apply_patch

Apply a unified diff via git apply (with a --3way fallback). cwd = repo root, patch = diff text.

write_file

Write full content to a file (overwrite, or append).

batch_read

Read several files in one call. files: array of { path, offset?, limit? }.

batch_edit

Apply many exact-text edits across one or more files in a single call. Transactional: every old_text is validated before any file is written, so a missing/ambiguous match aborts the whole batch (nothing changes). Each edit: { path, old_text, new_text, replace_all? }.

Native git passthrough

git_status (-sb), git_diff (staged + paths options), git_log (max_count, revision), git_show (revision). Each takes an optional cwd.

All file paths are resolved on the host running the server — they point at this machine, not Claude's sandbox.

Run locally

npm install
npm start
# server listens on http://localhost:3000/mcp

Optional env vars: PORT, CMD_TIMEOUT_MS, CMD_MAX_BUFFER.

npm start runs start.js, which frees port 3000 (kills any process holding it) before launching the server, so you never hit EADDRINUSE.

Expose it to Claude Desktop

Option A — Cloudflare Worker (stable URL, no trycloudflare, no domain needed)

A small local agent keeps a WebSocket open to a Cloudflare Worker, which becomes your stable public *.workers.dev MCP endpoint. The Worker only relays to your machine while the agent (authenticated with PROXY_SECRET) is connected.

1. wrangler login (free Cloudflare account).

2. Deploy: wrangler deploy → note your URL, e.g. https://command-line-mcp.<subdomain>.workers.dev.

3. Set the secret (same value already in your gitignored .dev.vars): wrangler secret put PROXY_SECRET (paste the PROXY_SECRET from .dev.vars).

4. Point the agent at the deployed Worker: set WORKER_URL in .dev.vars to that URL.

5. On your machine, run both:

   npm start          # the MCP server on :3000
   npm run agent      # connects to the Worker with the secret

6. In Claude Desktop: Customize → Connectors → Add custom connector, paste https://command-line-mcp.<subdomain>.workers.dev/mcp.

Local testing without deploying: wrangler dev --port 8787 (Worker on :8787), then npm run agent — the agent reads WORKER_URL from .dev.vars.

Option B — cloudflared / ngrok tunnel (ephemeral URL)

Claude Desktop connectors need an HTTPS URL, so run the server locally and tunnel it:

cloudflared tunnel --url http://localhost:3000 --protocol http2
# or: ngrok http 3000

Copy the generated https://… URL and append /mcp, e.g. https://abc-123.trycloudflare.com/mcp.

Add to Claude Desktop

1. Open Customize → Connectors → Add custom connector.

2. Paste the URL (with /mcp), e.g. the Worker URL from Option A.

3. Name it Command-Line.

4. Save. Claude discovers the OAuth metadata, registers a client, and opens a browser to the (auto-approving) authorize endpoint, then redirects back and is ready. No "OAuth Client ID" needs to be entered manually — DCR handles it.

Testing without Claude

Use the MCP Inspector:

npx @modelcontextprotocol/inspector
# Transport: Streamable HTTP, URL: http://localhost:3000/mcp

Hardening (for non-personal use)

OAuth is already implemented (see oauthProvider.js). For anything beyond a personal tunnel you should:

1. Replace the auto-approve authorize() with a real consent screen, or at least an allow-listed set of redirect URIs / clients.

2. Persist clients/tokens (currently in-memory — they reset on restart).

3. Host behind a stable HTTPS domain (e.g. a VPS, Cloudflare Workers, Fly.io).

4. Consider an allow-list of permitted commands to limit blast radius.

License

MIT