io.github.nries1/tend-mcp

tend-mcp

An unofficial MCP (Model Context Protocol) server for Tend dental — not affiliated with, endorsed by, or supported by Tend. It talks to internal API endpoints their own web app calls, discovered via browser devtools, not a published/documented API. Expect it to break without notice if Tend changes their frontend.

Use at your own risk. This has not been reviewed against Tend's Terms of Service — read them yourself before running this, and be ready to stop if Tend objects. Each instance authenticates as one Tend account and only ever accesses that account's own data; it is not designed or intended to access any other patient's records.

Status

Real, verified against a live HAR capture (2026-08-01) of an actual login → pick studio → pick service → pick time → book flow, plus live-tested auth: list_studios, list_service_types (static reference data — see below), list_appointments, search_available_slots, book_appointment (confirmed live — the capture includes a real booking that got a real Dentrix external_id).

Auth is fully real now — two ways in. Tend authenticates via AWS Cognito behind their own thin proxy at identity.hellotend.com. You can use either:

• TEND_PASSWORD — real email+password login (POST identity.hellotend.com/login, confirmed live), the same call the actual web app makes. No Cognito SRP dance needed client-side; Tend's backend handles that.
• TEND_REFRESH_TOKEN — skips login, obtained by hand once from DevTools (see below).

Either way, TendClient keeps itself signed in automatically: sessions renew via Cognito's REFRESH_TOKEN_AUTH (Authorization: Bearer <idToken>, ~24h tokens — confirmed live), falling back to a fresh password login if a refresh token expires/gets revoked and TEND_PASSWORD is set.

Setup

npm install
cp .env.example .env   # fill in TEND_EMAIL and (TEND_PASSWORD or TEND_REFRESH_TOKEN)
npm run dev             # or: npm run build && npm start

Point an MCP client (Claude Desktop, etc.) at it by adding to its MCP config, e.g. Claude Desktop's claude_desktop_config.json:

{
  "mcpServers": {
    "tend": {
      "command": "node",
      "args": ["/absolute/path/to/tend-mcp/dist/index.js"],
      "env": { "TEND_EMAIL": "you@example.com", "TEND_PASSWORD": "..." }
    }
  }
}

Getting a refresh token (if not using TEND_PASSWORD)

1. Log into hellotend.com in Chrome.
2. Open DevTools → Application → Cookies → hellotend.com.
3. Copy the value of the refreshToken cookie into TEND_REFRESH_TOKEN.

Both TEND_PASSWORD and TEND_REFRESH_TOKEN are standing credentials — treat them like a password, not an API key. A refresh token in particular can mint fresh sessions for a long time without re-entering anything. Never commit either, never paste either anywhere it might get logged — including into an AI chat. This isn't hypothetical: building this integration involved two real accidental exposures of live tokens into a chat session (once from a raw cookie paste, once from an incomplete redaction script missing token as a sensitive field name) — HAR "sanitization" and ad-hoc redaction scripts are not something to rely on. If you ever suspect either has leaked, log out of Tend everywhere / rotate your password.

Adding another endpoint

Log into hellotend.com, open DevTools → Network → Fetch/XHR, perform the action, and note the request. Then add a method to TendClient following the existing ones' shape (raw snake_case API fields mapped to a camelCase TS interface) and a corresponding tool in tools.ts.

If you export a HAR to work from: response bodies (not just headers) still contain real PII — redact personal fields (name, email, phone, insurance, DOB) out of them before sharing, and never share cookie/token values regardless of what the export tool does or doesn't strip automatically. .gitignore here already excludes *.har so it won't land in git.

Design constraints (please keep these)

• One account per instance. No multi-tenant credential store, no server-side proxy holding multiple users' logins.
• No anti-bot evasion. If Tend's login has MFA or bot-detection, surface it to the user (or fail loudly) rather than trying to automate around it.
• No endpoints beyond what a real patient portal already exposes to that patient. Don't add anything that reaches into other patients' data.
• STUDIOS/SERVICE_TYPES in tendClient.ts are a frozen snapshot, not live data. No stable API for them was found (see the comment above STUDIOS) — they'll silently go stale as Tend adds/closes studios or changes services. Worth periodically re-checking against a fresh capture rather than assuming they're current.