oneappsworld/callchatsyn-mcp

Let an AI assistant (Claude, Cursor, any MCP client) answer customer questions and book appointments for a small business, using that business's own FAQs and opening hours on CallChatSyn.
**Free for the first 1,000 businesses** (founder offer: 100 API calls a day, 2,000 a month).
Tools
| Tool | Changes data? | What it does |
|---|---|---|
| answer_customer_question | No (read-only) | Answers from the business's FAQs and order data (English/Chinese); flags booking and "talk to a person" requests |
| list_open_times | No (read-only) | Next open times (up to 5, next 7 days) in the business's time zone, plus services and locations; from CallChatSyn hours or the business's connected Cal.com |
| book_appointment | Yes, creates a booking | Books one of those times and returns its id; the business is notified and, with Cal.com connected, the booking is created there. Not idempotent. Demo key = dry run |
| cancel_appointment | Yes, cancels a booking | Cancels a booking by id (also in Cal.com if connected). To reschedule: cancel, then book a new time. Demo key = dry run |
Remote server (nothing to install)
Add this URL as a custom connector (Claude: Settings → Connectors → Add custom connector; Cursor and others: a Streamable HTTP server):
Without a key it uses the demo business. To act for your own business, send the header Authorization: Bearer ccs_live_.... Also listed in the official MCP Registry as com.callchatsyn/callchatsyn.
Local setup (npx)
1. Create a CallChatSyn account, add FAQs and opening hours, then Dashboard → Developers → claim founder access → create an API key.
2. Add to your MCP client config:
Keep the key private; it acts for one business.
No key yet? Leave CALLCHATSYN_API_KEY out and the server uses the public demo key (ccs_demo_public): answers come from a demo business and bookings are dry runs, so you can try every tool before signing up.