MCP Google Calendar Server

update_calendar_event

Update details of an existing calendar event, such as title, time, location, description, and attendees, by specifying the event ID.

Instructions

Update an existing calendar event

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "eventId": "<eventId>"
    },
    "name": "update_calendar_event"
  }
}

Input Schema

Name	Required	Description
`eventId`	Yes	The ID of the event to update
`summary`	No	Event title/summary
`description`	No	Event description
`startDateTime`	No	Start date and time in ISO format
`endDateTime`	No	End date and time in ISO format
`timeZone`	No	Time zone (e.g., America/Los_Angeles)
`attendees`	No	Array of attendee email addresses
`location`	No	Event location

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0May 31, 2026

TDQS

C2.8/5.0

Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden. It implies mutation but fails to disclose whether updates are partial or full, what side effects occur, or required permissions. This is insufficient for a mutation tool.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness3/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single sentence of 5 words, which is concise but lacks valuable context. It could include behavioral details without being overly long.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given 8 parameters and no output schema or annotations, the description is insufficient. It does not explain that only eventId is required, that other fields are optional, or how updates behave. This is incomplete for a complex update tool.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3. The description adds no extra meaning beyond what the input schema already provides for each parameter.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description 'Update an existing calendar event' clearly states the verb and resource. It distinguishes from sibling tools like 'create_calendar_event' and 'delete_calendar_event'. However, it does not specify the scope of updates or that it is a partial update.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance is provided on when to use this tool versus alternatives. There is no mention of prerequisites (e.g., authentication) or exclusion criteria. The sibling tools include authentication steps, but the description offers no context.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server