> ## Documentation Index
> Fetch the complete documentation index at: https://docs.automate.ax/llms.txt
> Use this file to discover all available pages before exploring further.

> ## Agent Instructions
> Automate.ax automations are TypeScript programs.
> Use Bun for installation and command examples.
> Use Automate.ax for the product name and automate.ax for the package, CLI, and domain.
> Treat documented public APIs as current; do not invent transitional or deprecated names.

# Update slot reservation

> Updates one Cal.com slot reservation.

`calcom.updateSlotReservation` updates one Cal.com slot reservation.

```ts automations/update-slot-reservation.automation.ts theme={null}
import { automation, markSignificant } from "automate.ax"
import { calcom } from "automate.ax/calcom"

export default automation("Update slot reservation", () => {
  markSignificant(
    calcom.updateSlotReservation({
      uid: "reservation-uid",
      eventTypeId: 23,
      slotStart: "2026-09-10T17:30:00.000Z",
    }),
  )
})
```

## Input

Pass these fields:

| Field                 | Type                 | Required | Description                                                                                                                                                                                                                                                                                  |
| --------------------- | -------------------- | -------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `uid`                 | `string`             | Yes      | —                                                                                                                                                                                                                                                                                            |
| `eventTypeId`         | `number`             | Yes      | The ID of the event type for which slot should be reserved.                                                                                                                                                                                                                                  |
| `slotStart`           | `string (date-time)` | Yes      | ISO 8601 date string in UTC representing the available slot.                                                                                                                                                                                                                                 |
| `slotDuration`        | `number`             | No       | By default slot duration is equal to event type length, but if you want to reserve a slot for an event type that has a variable length you can specify it here as a number in minutes. If you don't have this set explicitly that event type can have one of many lengths you can omit this. |
| `reservationDuration` | `number`             | No       | Reservation length in minutes for authenticated API key, access token, or OAuth requests. No one else can book the event type at `start` during this period. Defaults to 5 minutes.                                                                                                          |

## Output

Returns an object with these fields:

| Field                 | Type                 | Required | Description                                                                                                                                                                                                                                                           |
| --------------------- | -------------------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `eventTypeId`         | `number`             | Yes      | The ID of the event type for which slot was reserved.                                                                                                                                                                                                                 |
| `slotStart`           | `string (date-time)` | Yes      | ISO 8601 date string in UTC representing the available slot.                                                                                                                                                                                                          |
| `slotEnd`             | `string (date-time)` | Yes      | ISO 8601 date string in UTC representing the slot end.                                                                                                                                                                                                                |
| `slotDuration`        | `number`             | Yes      | By default slot duration is equal to event type length, but if you want to reserve a slot for an event type that has a variable length you can specify it here. If you don't have this set explicitly that event type can have one of many lengths you can omit this. |
| `reservationUid`      | `string`             | Yes      | The unique identifier of the reservation. Use it to update, get or delete the reservation.                                                                                                                                                                            |
| `reservationDuration` | `number`             | Yes      | Reservation length in minutes. No one else can book the event type at `start` during this period.                                                                                                                                                                     |
| `reservationUntil`    | `string (date-time)` | Yes      | ISO 8601 date string in UTC representing when the reservation expires.                                                                                                                                                                                                |

Cal.com enforces account role, plan, and availability requirements. Provider rejections surface as structured action failures with the HTTP status and any `Retry-After` delay.