CalendarSAFE

An MCP server that gives an LLM client read and write access to your Google Calendar. It runs as a single process — stdio by default, streamable HTTP optionally — and exposes 23 tools with structured output: listing and searching calendars and events, creating, updating, moving, RSVPing to and deleting events, free/busy queries, busyness analysis, recurring-event projection, and finding a mutual slot and booking it. On top of that it has a scheduling brain that knows your working hours: finding and booking focus time, detecting double-bookings across several accounts at once, proposing better times for a meeting, and auditing where your week actually went. Authentication is Google OAuth 2.0 (Desktop app flow); tokens are cached locally, per account, and refreshed automatically.

A calendar task, end to end

Synthetic example, backed by offline tests; no real calendar data or live booking. Assume Thursday working hours of 09:00–17:00 UTC, one meeting at 11:00–12:00, no lunch or buffer, and a 60-minute minimum focus block.

“Find six hours of focus time on January 1, 2026. Show me the blocks first.”

An MCP client can call:

{
"tool": "block_focus_time",
"arguments": {
"time_min": "2026-01-01T00:00:00Z",
"time_max": "2026-01-02T00:00:00Z",
"hours_needed": 6,
"dry_run": true
}
}

The preview selects 09:00–10:00 and 12:00–17:00: six hours, with the last selected block trimmed to the remaining hour. Both events have created: false. After the user approves the times, the client can call with dry_run: false; availability is read again before creating events. A preview does not reserve a slot.

Design decision: unknown availability is not free time. If a checked calendar returns an access error, disappears from the response, or has unreadable busy intervals, focus search and booking return an error before writing anything. The same check protects mutual scheduling and reschedule suggestions/application. For