I would not call it a webhook function. I usually say tools call. simple prompts like this work: Gather Information & Trigger Booking: -By asking the information like name,phone,email and date for booking start triggering the trigger the "book_calendar_ghl" function.Once you trigger the function then check the calender and reply back to caller as"Your slot is booked on calender.if the caller is saying a slot which is not available ask to them another slot.