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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

1

Open the event type

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

Read the ID from the URL

The event type ID is the number in the address bar, for example https://app.cal.com/event-types/1234567 — the ID is 1234567.
3

Paste it into the tool

Enter that number in the tool’s event type ID input. Point a separate tool at each event type you want the agent to handle.
A Cal.com event type named 30 min meeting open on its Basics tab, with title, description, duration, and location settings. The browser address bar is highlighted with a blue ring, showing app.cal.com/event-types/ followed by the event type ID, which is redacted in this shot.

An event type open in Cal.com — the event type ID is the number after /event-types/ 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 be an event type the connected account can book, and the ID must match the number in the event type’s URL. Then check the event type 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.
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.