Will updating an event notify the attendees?

The change is saved to your local Calendar.app, and Calendar handles invitee updates the same way it would for a manual edit. You can also ask your AI to send a heads-up email via LMCP's send_email tool.

Do I have to specify every field when I update an event?

No. update_calendar_event only changes the fields you pass. If you only want to move the time, the title, location, notes and attendees all stay exactly as they were.

How does the AI know which event to update?

It first looks up the event — usually with list_calendar_events — to get the event's ID, then updates by that ID. So a prompt like 'move my 3pm meeting' resolves to the right entry on your live calendar.

Is my calendar data sent to the cloud?

No. LMCP runs entirely on your Mac and edits Calendar.app directly. There are no API keys and nothing is stored on a server, so your schedule never leaves your machine.

Update a Calendar Event on Mac with AI

update_calendar_event lets your AI assistant edit an existing event in the Mac's Calendar app (Calendar.app) by its ID. You pass only the fields you want to change — the start time, end time, title, location, notes or attendees — and everything else stays untouched. Instead of opening Calendar, finding the event and dragging it around, you just say what you want. A typical prompt: "Move my 3pm dentist appointment tomorrow to 4:30pm and add a note that I need to bring my insurance card." The AI finds the event, updates only those fields, and saves it back to your real calendar.

Because the tool updates by ID and only touches the fields you specify, it is safe for surgical edits. You can change a single meeting's location without disturbing its time, recurrence, or invitees. Download LMCP to enable it.

Which AI agents work?

LMCP works with every major AI client. Desktop clients auto-configure over a local stdio connection — no manual setup:

Claude Desktop
Cursor
VS Code (GitHub Copilot)
Windsurf
Zed

Web-based AIs connect through the LMCP Cloud Relay connector, which securely bridges the assistant to your Mac:

ChatGPT
Claude.ai (web)
Grok
Perplexity

Automation

update_calendar_event is most powerful when chained with other LMCP tools. A common flow: the AI uses list_calendar_events to find the event you mean, grabs its ID, then calls update_calendar_event to apply the change. From there it can chain into send_email to notify attendees of the new time, or create_reminder to set a follow-up. You can also combine it with search_messages or read_email — "a client emailed asking to push our call an hour later, update the calendar event accordingly" — and the assistant resolves the whole task end to end across 150+ tools.

Context

The AI is working with your real Mac data, not a guess. It reads the actual events on your calendars, knows their true start and end times, sees existing notes and locations, and edits the genuine entry in Calendar.app. There is no parallel copy to fall out of sync. When you say "my next standup," it resolves that against your live schedule, so the edit lands on the right event every time.

Productivity

Rescheduling by hand means opening Calendar, scrolling to the day, double-clicking the event, fixing the time, and saving — repeated for every change. With update_calendar_event you describe the change in plain language and it is done in seconds. Batch reschedules ("push all my Friday meetings 30 minutes later") that would take minutes of clicking become a single sentence. For anyone who lives in their calendar, that is real time back every day.

Privacy & GDPR

Everything runs locally on your Mac. LMCP is a native macOS MCP server: it talks directly to Calendar.app on your machine, with no API keys and no data sent to or stored on any server. Your events never leave your computer. This makes LMCP GDPR-compliant by architecture — there is no cloud copy of your schedule to leak or subpoena, because the processing happens entirely on the device you control.