Donut's Google Calendar integration allows users of Donut Intros to automatically find a time that works for everyone and add an event to their calendars.
Donut uses 2 permissions, also known as scopes, to accomplish this:
calendar.readonly
On Google's authorization page this appears as, "See and download any calendar you can access using your Google Calendar."
This scope is necessary for Donut to find a time when all parties are free. This is done with Google's Freebusy API.
This scope also grants access to other APIs that Donut does not use.
calendar.events
On Google's authorization page this appears as, "View and edit events on all your calendars."
This scope is necessary for Donut to add an event to the calendar. This is done with the Events insert API.
This scope is also used in some cases to update and delete the events that are created by Donut. This is done with the Events patch and Events delete APIs.
This scope also grants access to other APIs that Donut does not use.