# Error using book appointment feature for cal.com **URL:** \ **Category:** Support Help\ **Tags:** integrations\ **Created:** [March 10, 2026, 7:35pm UTC](https://community.retellai.com/t/error-using-book-appointment-feature-for-cal-com/1017 "2026-03-10T19:35:41Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![chettabox](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/chettabox/32/997_2.png) [@chettabox](https://community.retellai.com/u/chettabox)\ **Post date:** [March 10, 2026, 7:35pm UTC](https://community.retellai.com/t/error-using-book-appointment-feature-for-cal-com/1017/1 "2026-03-10T19:35:41Z")
Hi everyone, I am building an inbound call agent. I am able to add the function ‘check\_availability’ from [cal.com](http://cal.com) with the API key and eventid but can’t do it for the ‘book\_appointment’ function. The requirements for both are exactly the same, the API key and event id. But for some reason ‘book\_appointment’ doesn’t work. It throws off an error saying: Error validating [cal.com](http://cal.com) tools. ---
**Author:** ![support2](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/support2/32/15_2.png) [@support2](https://community.retellai.com/u/support2)\ **Post date:** [March 10, 2026, 7:45pm UTC](https://community.retellai.com/t/error-using-book-appointment-feature-for-cal-com/1017/2 "2026-03-10T19:45:52Z")
Thank you for reaching out to Retell AI Support. We’ve received your ticket and our team will respond within 8 hours. ![](https://canada1.discourse-cdn.com/flex008/uploads/retell1/original/1X/f790e262d20d980f4c847beba41a60ec3c6dbcee.png) ---
**Author:** ![support2](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/support2/32/15_2.png) [@support2](https://community.retellai.com/u/support2)\ **Post date:** [March 10, 2026, 7:46pm UTC](https://community.retellai.com/t/error-using-book-appointment-feature-for-cal-com/1017/3 "2026-03-10T19:46:05Z")
Hi Retell, Here are some resources to help you with your [Cal.com](http://Cal.com) integration: - **Video Tutorials** : Access introductory videos for integration setup at Retell AI Docs: [https://docs.retellai.com/videos/introduction](https://docs.retellai.com/videos/introduction) - **Webinars** : Watch detailed webinars on integration best practices at Retell AI YouTube Playlist: [https://www.youtube.com/watch?v=A9H3a33gM2M&list=PLGrX1\_bbFSHrD6DnoHnQw08nmAH\_B3efs](https://www.youtube.com/watch?v=A9H3a33gM2M&list=PLGrX1_bbFSHrD6DnoHnQw08nmAH_B3efs) - **Forum Community** : Join the community for real-time support at Retell AI Forum: [https://community.retellai.com/invites/wzFwjPvch9](https://community.retellai.com/invites/wzFwjPvch9) - **Discord Community/Office Hours** : Join our Discord for live support: [https://discord.com/invite/wxtjkjj2zp](https://discord.com/invite/wxtjkjj2zp) - **Hire A Developer Program** : Connect with professional developers for personalized assistance: [https://retellai.retool.com/form/888fc4e3-fdd3-4de3-8434-d8ae68d35fc8](https://retellai.retool.com/form/888fc4e3-fdd3-4de3-8434-d8ae68d35fc8) Best, Evy AI AI Support Agent @ Retell AI ![](https://canada1.discourse-cdn.com/flex008/uploads/retell1/original/1X/f790e262d20d980f4c847beba41a60ec3c6dbcee.png) ---
**Author:** ![chettabox](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/chettabox/32/997_2.png) [@chettabox](https://community.retellai.com/u/chettabox)\ **Post date:** [March 11, 2026, 2:35pm UTC](https://community.retellai.com/t/error-using-book-appointment-feature-for-cal-com/1017/4 "2026-03-11T14:35:26Z")
Looks like the issue has been resolved - I recreated my [Cal.com](http://Cal.com) account , tested it an it works. Not sure if that was the issue or if some issue was fixed on the Retell side ---
**Author:** ![support2](https://yyz2.discourse-cdn.com/flex008/user_avatar/community.retellai.com/support2/32/15_2.png) [@support2](https://community.retellai.com/u/support2)\ **Post date:** [March 11, 2026, 2:45pm UTC](https://community.retellai.com/t/error-using-book-appointment-feature-for-cal-com/1017/5 "2026-03-11T14:45:44Z")
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