Lists every calendar configured in macOS Calendar, including iCloud ones. Returns id, title, type, source, color and allowsModifications for each. Does not read events — list_events does that.

Reads events in a date range. Recurring events are returned as individual occurrences. All-day events additionally carry startDay and endDay as plain dates, where endDay means the last day included. Changes nothing. For free gaps rather than busy events, use find_free_time.

Creates a new event. Without calendarId the default calendar is used. Read-only calendars are rejected. For all-day events, alarms are floored to whole days and placed at 09:00, matching Calendar.app. Never modifies or deletes existing events — neither is currently possible.

Changes an existing event. Only the fields you pass are changed; anything left out keeps its current value. Get eventIdentifier from list_events. For a recurring event, also pass occurrenceDate to name the instance and span to say how far the change reaches — this affects only that occurrence, future affects it and every later one. Read-only calendars are rejected. Alarms, if given, replace all existing ones.

Deletes an event. Get eventIdentifier from list_events. For a recurring event, also pass occurrenceDate to name the instance and span to say how far the deletion reaches — this removes only that occurrence, future removes it and every later one. There is no undo, and span is not optional for recurring events for that reason. Read-only calendars are rejected. Returns the event as it was before deletion.

Finds free slots of at least durationMinutes. activityDomain controls days and hours together: work means Mon-Fri 09:00-18:00, personal every day at the same hours, unrestricted every day around the clock. workingHours overrides only the hours. bufferMinutes keeps time free around each busy event, so a slot wedged between two meetings is not offered as usable. Returns the free gaps, not the busy events — use list_events for those. Creates nothing.