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A connected Cal.com account gives your agents the full booking lifecycle as live tools: check availability, book, and list, get, reschedule, or cancel bookings. Tools run during a conversation or before and after it. There’s no synced copy of your calendar in Retell; every tool call reads or writes Cal.com live.

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Available tools

These tools appear in your agent’s function menu once your account is connected. Check Availability and Book Appointment each take an event type ID, so they’re pinned to one event type. See use integration tools in an agent for how to add and configure them.
Chain the tools: List Bookings finds the booking UID by the caller’s email, Check Availability confirms the new slot exists, and Reschedule Booking moves it. Map the UID from the list result to a dynamic variable so the later tools can use it.

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Find an event type ID

Cal.com now calls event types links, and its dashboard shows a link’s ID instead of the numeric event type ID. The tool accepts either, so tools that already have a numeric ID keep working.
1

Open the link

In the Cal.com dashboard, open Links and select the one the agent should book.
2

Copy the link ID

The link ID is the part of the address after /links/, up to any ?. In https://app.cal.com/links/1cBDsFTQV6qXPjkbeb1gwW?tabName=setup, it’s 1cBDsFTQV6qXPjkbeb1gwW. Copy only the ID, not the whole URL.
3

Paste it into the tool and save

Enter the ID in the tool’s event type ID input and save. Retell looks up the link and stores its numeric event type ID in place of the link ID, so the input shows a number when you reopen the tool. Point a separate tool at each link you want the agent to handle.
The Cal.com dashboard with the 30 min meeting link open on its Basics tab, showing its Title and Description fields. In the browser address bar, app.cal.com/links/ is followed by the link ID 1cBDsFTQV6qXPjkbeb1gwW, outlined in a blue box.

A link open in Cal.com, with its link ID outlined in the address bar.

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Permissions

The API key grants the connected account’s full API access; there are no per-tool scopes to grant. Every tool reads the connected account’s event types and reads and writes its bookings.

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Troubleshooting

Check the event type ID on the tool: it must belong to a link the connected account can book. Then check the link on Cal.com: it needs open hours in the window the agent asked about, and its calendar (Google, Outlook, and so on) must be connected under Apps so Cal.com can read your busy times.
Enter a link ID or a numeric event type ID, not the full URL or the link’s slug. The connected Cal.com account must also have access to the link.
The lookup matches on the attendee email within the time window the agent supplies. Have the agent confirm the email used to book, and if the booking might sit outside the window, widen it.

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FAQ

You can no longer add a built-in Cal.com tool from the dashboard, and the API stops creating and updating them on 09/30/2026, so that’s your last day to change a built-in tool’s key or event type ID. Existing tools keep running until 10/31/2026, when Retell migrates them to this integration: it sets up one connection per API key it finds, reusing a connection you’ve already made for that key, and keeps each tool’s function name so your prompts don’t break. A tool whose key Cal.com rejects, because it expired or was revoked, is skipped and stops working, so migrate that one by hand: connect Cal.com, add Check Availability and Book Appointment with the same event type ID, and delete the built-in tool. See the deprecation notice for the full timeline.
Calendly covers availability, booking, and cancellation, and GoHighLevel calendars cover the full lifecycle when your scheduling sits in the same sub-account as your contacts.
Yes. Bookings, reschedules, and cancellations go through Cal.com, so attendees get exactly the notifications and calendar invites your event type is configured to send.

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Next steps

Integration tools for prompt agents

Add Cal.com tools to a single- or multi-prompt agent and test them with live requests.

Integration tools in conversation flow

Call Cal.com tools from a function node and branch on the result.

Dynamic variables

Carry booking UIDs and confirmed times between tools and prompts.

Simulation testing

Mock the booking tools to test your scheduling flow without creating real bookings.