Kalender Sync

Update event

update_event

Destructive

Updates an event. title, start and end describe the complete new state — including whether it is all-day: an event created all-day becomes a timed event if this call passes timestamps, and vice versa.

Two kinds of event are addressable:

Events THIS access created (via event_id from create_event) — always.
Any other event in a calendar the user allowed managing, visible in list_calendars as manageable: true. Their ids come from get_availability.

Four things are refused, and each says what to do instead — pass that on rather than retrying: • the calendar is not released for managing (the user can allow it per calendar) • it is shared at less than full detail (a setting, not a temporary error) • the event is a synchronised COPY — change the original in the named source calendar, the change reaches this one by itself • someone else organises it — call respond_to_event with response: "declined" and the same event_id instead

Input Schema

TableJSON Schema

Name	Required	Description
`end`	Yes	New end — same form as `start`; INCLUSIVE for all-day events.
`start`	Yes	New start — ISO 8601 with timezone (…+02:00 or …Z), or a bare date (2026-07-28) for an all-day event.
`title`	Yes
`all_day`	No	Force an all-day event; time components in start/end are discarded.
`event_id`	Yes	Identifier from create_event
`location`	No
`time_zone`	No	IANA zone, e.g. America/New_York. Preserves the named zone for timed events (so recurrences follow daylight saving) and decides the local day for all-day ones. Defaults to UTC.
`calendar_id`	No
`description`	No

Output Schema

TableJSON Schema

Name	Required	Description	Default
`updated`	Yes
`event_id`	Yes
`calendar_id`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedAug 28, 2026

changedInput schema / properties / time_zone / description

Previous value: -"IANA zone deciding which local day an all-day event covers. Defaults to UTC."New value: +"IANA zone, e.g. America/New_York. Preserves the named zone for timed events (so recurrences follow daylight saving) and decides the local day for all-day ones. Defaults to UTC."

Changed4 schema fields changedAug 27, 2026

addedInput schema / properties / all_day

Added value: +{
+  "description": "Force an all-day event; time components in start/end are discarded.",
+  "type": "boolean"
+}

changedInput schema / properties / end / description

Previous value: -"New end, ISO 8601 with timezone"New value: +"New end — same form as `start`; INCLUSIVE for all-day events."

changedInput schema / properties / start / description

Previous value: -"New start, ISO 8601 with timezone (e.g. …+02:00 or …Z)"New value: +"New start — ISO 8601 with timezone (…+02:00 or …Z), or a bare date (2026-07-28) for an all-day event."

addedInput schema / properties / time_zone

Added value: +{
+  "description": "IANA zone deciding which local day an all-day event covers. Defaults to UTC.",
+  "type": "string"
+}

First observedJul 31, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Annotations already establish the destructive/mutating profile, and the description adds substantive behavioral context beyond them: the all-day↔timed conversion, complete-new-state semantics, and all four refusal modes with remediation. These are meaningful details the structured fields could not convey, and they are consistent with readOnlyHint=false and destructiveHint=true.

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

Conciseness4/5

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

The description is long, but every sentence earns its place — the numbered event-addressability list and bulleted refusal cases are scannable and front-loaded. Minor trims are possible in the parenthetical clarifications, but there is no padding or repetition.

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

Completeness4/5

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

For a 9-parameter, 4-refusal-case tool with two addressability modes, nearly everything an agent needs is present, and the output schema covers the response contract. The only gap is the fate of unspecified optional fields (description, location) given that only title/start/end are declared 'complete new state'.

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

Parameters4/5

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

Schema coverage is only 56%, and the description compensates well by explaining that title/start/end constitute the complete new state and how passing timestamps vs. bare dates flips an event between all-day and timed. It leaves format details (ISO 8601, IANA zones) to the schema as appropriate, but does not clarify what happens to optional fields like location or description when omitted.

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

Purpose5/5

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

The description uses a specific verb and resource ('Updates an event') and immediately defines what that means — title/start/end describe the complete new state, including the all-day nuance. It also references sibling tools (create_event, respond_to_event, list_calendars) so an agent can distinguish this from create/delete/respond flows without inspecting schemas.

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

Usage Guidelines5/5

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

This is exemplary. The description explicitly states the two kinds of events that are addressable and enumerates all four refused cases, each with 'what to do instead' — routing to respond_to_event with response: 'declined' for organizer conflicts and to the source calendar for synced copies. Nothing is left to inference.

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

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