Vapi + Make + calendly availibilty tool still runs but appointment flow still fails

Im new to AI automations and I’m trying to build a VAPI + Make + Calendly appointment booking system.

The flow is supposed to work like this:

  • Caller gives preferred date/time
  • VAPI calls Make through a tool
  • Make checks Calendly busy times
  • Make returns availability back to VAPI
  • VAPI only books the appointment if the time is available

The Calendly API call seems to work and returns busy times, but the VAPI/tool response or prompt logic still isn’t working correctly.

Here’s a screen recording walking through the setup:
https://drive.google.com/file/d/1Zj8eciwQpwwuJt6r0IY8Uyvr9SqNma15/view?usp=sharing

Main issue:
When i test it, it seems like vapi ignores the already booked appointments/busy times.

Expected result:
VAPI should check availability first, then only book if the time is available.

Any help pointing out what I mapped wrong or what my webhook response should look like would be appreciated.