### Answer --- Based on the available documentation, the built-in

check_calendar_availability

function in Retell uses a specific Event Type ID from Cal.com to determine which calendar to query. [(1) ]() To return availability for only one specific calendar: 1. In your Cal.com dashboard, open the specific event type you want to use 2. Get that event type's unique ID from the URL (e.g., ` — the ID is

1427703

) 3. When configuring the check calendar availability function in Retell, enter only that specific Event Type ID If you're currently getting availability from all 4 calendars, it's likely because: - You may have multiple availability functions configured with different Event Type IDs - Or the Cal.com event type itself is linked to multiple calendars (e.g., using round robin) For more granular control over which calendar is queried, community members have suggested implementing a custom function with your own backend logic rather than relying solely on the built-in integration. [(2) ]() Check out these potentially useful sources: [Check Calendar Availability]() , [Custom Function Documentation]() Would you like me to try to answer more generally about how to filter calendar results?

​ To learn more, see the sources I considered: [[1] Check Calendar Availability](https://docs.retellai.com/build/check-availability) [[2] Calendar Availability](https://discord.com/channels/1186424376300679209/1395791084709347399) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.

@AI Evy This is not being done using Cal.com. The issue i'm having is that the available slots are being truncated because the response exceeds 15000 characters.

### Answer --- Based on a Discord discussion, tool results in Retell have a 4,000 character limit. [(1) ]() Since you're dealing with availability data from 4 calendars that exceeds 15,000 characters, you'll need to reduce the response size in your custom function before returning it to Retell. Here are some approaches: 1. Filter on your backend – Before returning the tool result, filter the availability data to only include the specific calendar you need, rather than all 4 calendars 2. Reduce the date range – One community member noted their custom calendar integration could only provide results for 12-14 days max due to this limit 3. Simplify the response format – Return only essential fields (e.g., just the time slots) rather than full calendar objects 4. Paginate or summarize – Return availability in smaller chunks or provide a summary that fits within the character limit The key is to handle the filtering and data reduction in your custom function's backend logic before sending the result back to Retell. Check out these potentially useful sources: [Live Workshop: Retell x GoHighLevel Integration]() Would you like a general answer on how to structure a custom calendar function to handle this filtering?

​ To learn more, see the sources I considered: [[1] Does Tool Result have character limit?](https://discord.com/channels/1186424376300679209/1342230007136911493) ​

Feel free to tag @AI Evy with additional questions. I also appreciate feedback, it helps me improve.