# mcp-server-withings

MCP server for the [Withings Health API](https://developer.withings.com/) with **per-user OAuth2** — each user links their own Withings account and can only ever see their own health data.

## How isolation works

Behind an authenticating gateway that forwards the signed-in user as `X-MCP-User`, every tool is bound to that user. The server keeps an **AES-256-GCM encrypted, per-user token store**; a user's identity resolves only to their own row. Without a verified identity the server fails closed (no anonymous/shared access). Each user enrolls once via `withings_connect`, which returns a single-use Withings authorization URL bound to them; after they approve in the browser, `/withings/callback` stores their (encrypted) tokens.

## Tools

**Auth/enrollment:** `withings_connect`, `withings_status`, `withings_disconnect`.
**Read:** `withings_get_measures`, `withings_get_activity`, `withings_get_sleep`, `withings_get_workouts`, `withings_get_heart`, `withings_get_devices`, `withings_get_goals`, `withings_search_capabilities`.
**Write (opt-in `WITHINGS_ENABLE_WRITES=true`):** `withings_add_measure`.

## Configuration

See `.env.example`. Register a Withings app at account.withings.com; the redirect URI must match `WITHINGS_REDIRECT_URI` exactly and be publicly reachable (route `/withings/callback` to this container). Set `WITHINGS_ENCRYPTION_KEY` (never commit) and `WITHINGS_TRUST_FORWARDED_USER=true` behind the gateway.

## Run

```bash
npm install
npm run dev:http     # /mcp + /withings/callback on :3000
npm test
```

Docker images: `ghcr.io/borgels/mcp-server-withings`.