update_event

SERVERMcp Google Calendar SOURCE@a1-x-tech/mcp-google-calendar

Medium RISK CLASS

Category Write

Parameters 121 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/a1-x-tech-mcp-google-calendar/update-event.md

WHAT IT DOES

What update_event does on Mcp Google Calendar

AI agents use update_event to create or update resources in Mcp Google Calendar, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Mcp Google Calendar environment.

Parameter	Type	Required	Description
`summary`	string	—	New event title.
`add_meet`	boolean	—	Attach a Google Meet conference. The returned conferenceData may be status=pending — re-run get_event for the final Meet link.
`color_id`	string	—	Event color id ("1".."11"; the palette is fixed by Google).
`end_date`	string	—	All-day event end date, EXCLUSIVE — the day after the last day (a one-day event on the 5th ends on the 6th).
`event_id`	string	Yes	The event id from list_events or create_event output. A recurring-instance id (masterId_20260101T100000Z from list_event_instances) addresses one occurrence.
`location`	string	—	Free-form location, e.g. a room name or address.
`attendees`	array	—	Guest list. On update this REPLACES the whole list — fetch the event first and send the complete new list. Invitation emails go out only with send_updates=all.
`reminders`	array	—	Custom reminders (max 5). Setting this turns default reminders off for the event.
`time_zone`	string	—	IANA time zone for start/end (e.g. "Europe/Berlin"). REQUIRED for recurring events; otherwise optional when the RFC3339 offsets already say everything.
`recurrence`	array	—	RRULE/RDATE/EXRULE/EXDATE lines (RFC 5545) making the event recurring, e.g. ["RRULE:FREQ=WEEKLY;BYDAY=MO,WE"]. Requires the timed pair plus time_zone.
`start_date`	string	—	All-day event start date (YYYY-MM-DD). Pair with end_date.
`visibility`	string	—	Who can see event details on a shared calendar.

Parameters from the server's own tool schema.

RISK

Why update_event is rated Medium

An AI agent can call update_event faster than any human can review: one bad instruction and it creates or modifies resources in Mcp Google Calendar by the hundred, each call as confident as the last.

Risk signalsHigh parameter count (26 properties) · Bulk/mass operation — affects multiple targets

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs update_event safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Mcp Google Calendar, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For update_event, this is the rule to start with:

update_event Rate-limited

update_event stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "update_event": {
      "limits": [
        {
          "counter": "update_event_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Mcp Google Calendar, apply this rule, and every update_event call is checked against it from then on.

FAQ

Questions about update_event

What does the update_event tool do? +

Partially updates an event (PATCH): only the provided fields change, but a provided nested object REPLACES its predecessor wholesale — attendees replaces the entire guest list (get_event first, send the complete new list), reminders replaces all overrides, and a time change should carry BOTH the new start and end (start_date_time + end_date_time, or start_date + end_date). To reschedule one occurrence of a recurring series, pass that instance's id (from list_event_instances) as event_id; passing the series master id changes every occurrence. Guests hear about the change only with send_updates=all. Also works to update Out of Office / Focus Time blocks. Returns the updated event. It is categorised as a Write tool in the Mcp Google Calendar MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does update_event accept? +

update_event accepts 12 parameters: summary, add_meet, color_id, end_date, event_id, location, attendees, reminders, time_zone, recurrence, start_date, visibility. Required: event_id. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on update_event? +

Register the Mcp Google Calendar MCP server in PolicyLayer and add a rule for update_event: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Mcp Google Calendar. Nothing to install.

What risk level is update_event? +

update_event is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit update_event? +

Yes. Add a rate_limit block to the update_event rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block update_event completely? +

Set action: deny in the PolicyLayer policy for update_event. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides update_event? +

update_event is provided by the Mcp Google Calendar MCP server (@a1-x-tech/mcp-google-calendar). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

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