Google Calendar checkAvailability Tool Not Preventing Double Bookings Vapi AI #support

Google Calendar checkAvailability Tool Not Prevent...

dodomin

10/20/2025, 2:41 PM

Hi, checkAvailability Tool is retreiving no busy arrays even if in google calendar there is a meeting. Everywhere I set up America/New_York timezone. I have tried checking periods with start_time - 5min and end_time + 5min and creating event that is starting day before and ending day after, but it did not work. Do you have any idea how to solve it? https://cdn.discordapp.com/attachments/1429842020222111866/1429842020473634917/image.png?ex=6942c126&is=69416fa6&hm=cc39a38e0efb7f565fe8b9d98bfb11c88d04f60435a58e2011a6ba4785bee396&

Vapi Support Bot

10/20/2025, 2:43 PM

Try explicitly setting the
calendarId
in your checkAvailability tool call to ensure you're querying the correct calendar. By default, the tool checks only the primary calendar, so if your meetings are in a different calendar, they won't appear as busy slots. Example:

Copy code

json
{
  "startDateTime": "2025-10-21T10:55:00",
  "endDateTime": "2025-10-21T11:50:00",
  "timeZone": "America/New_York",
  "calendarId": "your-calendar-id"
}

Update your request with the correct

calendarId

and test again in the dashboard's tool testing section for accurate results. Reference: Google Calendar Integration documentation Source: - [Google Calendar Integration documentation](https://docs.vapi.ai/tools/google-calendar)

GIDEON

10/20/2025, 8:36 PM

I have a workflow on make.com that doesn’t double-book you might want to check them out..

GIDEON

10/20/2025, 8:37 PM

@dodomin https://www.loom.com/share/23bf239793a24fb38feefbeacb0177a2?sid=5591f170-8fda-4bfa-90ee-9cfc1f63b8eb

GIDEON

10/20/2025, 8:38 PM

Check out the loom video to confirm..

Chiranjeet Mishra

10/21/2025, 6:55 PM

Hi dodomin, To integrate Google Calendar with your Vapi assistant: 1. **Connect Google Account**: Authorize Google Calendar access via the Vapi Dashboard under Providers Keys > Tools Provider > Google Calendar. Click Connect and follow the prompts. 2. **Create Tools**: Go to Dashboard > Tools and create the necessary tools, such as the Google Calendar Create Event Tool and Google Calendar Check Availability Tool. 3. **Add Tools to Assistant**: In Dashboard > Assistants, choose your assistant, go to the Tools tab, and add the Google Calendar tools. Click Publish to save. Ensure to verify the correct timezone and calendar ID usage, and check your assistant's logic to prevent double bookings by always performing availability checks before creating events. For more details, see the [Google Calendar Integration](https://docs.vapi.ai/tools/google-calendar).

Haley

10/22/2025, 3:00 PM

Hi! Just adding in here that we're seeing the check availability tool also returning time slots that are already booked for the connected calendar. Is there an ETA on when a fix is expected for this?

dodomin

10/23/2025, 2:12 PM

@User im trying to do this in your dashboard - not as api call.

Chiranjeet Mishra

10/24/2025, 6:16 PM

We’ll share an update as soon as we have more information. Thank you for bearing with us and for your patience while we work to get everything back to normal.

mathes0n

11/19/2025, 9:42 PM

Are there any updates to this topic? Same issue

Chiranjeet Mishra

11/21/2025, 9:36 PM

Hi there, If your Google Calendar shows busy times as available, this is usually caused by a timezone mismatch. The

checkAvailability

tool expects the start and end times in UTC, so if your prompt or assistant uses local time without converting, it will treat busy times as free. Here’s a prompt that has helped many users avoid double booking:

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## scheduling appointments
ask the user what day and time they want to schedule an appointment. assume all appointments are 1 hour long and are all in PST timezone (UTC-7). once you get the desired day and time for the appointment, convert the day and time to UTC+0 timezone equivalent, then use the 'google_check' tool to check if the desired day and time is available. if it is not available, apologize then suggest a different time. if it is available, tell the user it is available and ask if they would like to schedule the appointment for this time. if they say yes, use the 'google_schedule' tool to create the event for the day and time in the UTC+0 timezone equivalent. if they say no, then tell them it's okay and you understand their decision.

Key takeaway: Always convert times to UTC before calling the tool. If after applying this you still see the issue, please let us know — we’re happy to help troubleshoot further.

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