Did you check with Vapi AI already? Keep points to check: 1. Calendar ID: Make sure you've provided the correct calendarId when setting up the Check Availability and Create Event tools. You can find your calendar ID in GoHighLevel under Settings > Calendars. 2. Tool Setup Sequence: Verify you have all four required tools set up: Get Contact Create Contact Check Availability Create Event 3. Tool Dependencies: Remember that you need a contactId before you can book appointments. The workflow should be: First use Get Contact to check if contact exists If not, use Create Contact to make a new contact Then check availability Finally create the event 4. System Prompt: Ensure your assistant's system prompt includes clear instructions about the booking workflow and timezone handling. Check if you've specified the correct timezone in your tool metadata. 5. Time Format: Make sure the startDate and endDate parameters for availability checks are properly formatted in epoch time milliseconds.