Local MCP

Update Calendar Event

update_calendar_event

Destructive

Updates an existing event in the Mac's Calendar app (Calendar.app) by ID. Pass only the fields you want to change — unspecified fields are left as-is. Get the event_id from list_calendar_events; for a recurring event, pass the per-occurrence id from the specific row you mean, not a bare series id. For Microsoft 365 use the m365 calendar tools instead.

Input Schema

TableJSON Schema

Name	Required	Description
`span`	No	For recurring events: 'this' (default — only this occurrence) or 'future' (this and all following occurrences; 'all'/'series' mean the same). Any other value is refused.
`notes`	No	New notes — pass empty string to clear (optional)
`title`	No	New title (optional)
`confirm`	No	Must be true to apply changes
`end_date`	No	New end datetime ISO 8601 (optional). Same timezone rules as start_date.
`event_id`	Yes	Event (or occurrence) identifier from list_calendar_events. For a recurring event this addresses exactly the occurrence that id came from — the preview names the date and scope so you can confirm before applying.
`location`	No	New location — pass empty string to clear (optional)
`start_date`	No	New start datetime ISO 8601 (optional). No timezone = Mac's local time; append Z/offset to pin the zone.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`id`	No
`end`	No
`notes`	No
`start`	No
`title`	No
`all_day`	No
`updated`	No
`calendar`	No
`location`	No
`attendees`	No
`calendar_id`	No
`attendees_total`	No

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedSep 30, 2026

changedInput schema / properties / event_id / description

Previous value: -"Event identifier from list_calendar_events"New value: +"Event (or occurrence) identifier from list_calendar_events. For a recurring event this addresses exactly the occurrence that id came from — the preview names the date and scope so you can confirm before applying."

changedInput schema / properties / span / description

Previous value: -"For recurring events: 'this' (default) or 'future'"New value: +"For recurring events: 'this' (default — only this occurrence) or 'future' (this and all following occurrences; 'all'/'series' mean the same). Any other value is refused."

Changed2 schema fields changedSep 29, 2026

changedInput schema / properties / event_id / description

Previous value: -"Event (or occurrence) identifier from list_calendar_events. For a recurring event this addresses exactly the occurrence that id came from — the preview names the date and scope so you can confirm before applying."New value: +"Event identifier from list_calendar_events"

changedInput schema / properties / span / description

Previous value: -"For recurring events: 'this' (default — only this occurrence) or 'future' (this and all following occurrences; 'all'/'series' mean the same). Any other value is refused."New value: +"For recurring events: 'this' (default) or 'future'"

Changed1 schema field changedSep 26, 2026

changedInput schema / properties / span / description

Previous value: -"For recurring events: 'this' (default) or 'future'"New value: +"For recurring events: 'this' (default — only this occurrence) or 'future' (this and all following occurrences; 'all'/'series' mean the same). Any other value is refused."

Changed1 schema field changedSep 26, 2026

changedInput schema / properties / event_id / description

Previous value: -"Event identifier from list_calendar_events"New value: +"Event (or occurrence) identifier from list_calendar_events. For a recurring event this addresses exactly the occurrence that id came from — the preview names the date and scope so you can confirm before applying."

Changed2 schema fields changedJul 30, 2026

changedInput schema / properties / end_date / description

Previous value: -"New end datetime ISO 8601 (optional)"New value: +"New end datetime ISO 8601 (optional). Same timezone rules as start_date."

changedInput schema / properties / start_date / description

Previous value: -"New start datetime ISO 8601 (optional)"New value: +"New start datetime ISO 8601 (optional). No timezone = Mac's local time; append Z/offset to pin the zone."

First observedJun 30, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already declare readOnlyHint=false and destructiveHint=true, so the safety profile is covered. The description adds genuinely useful behavior beyond that: unspecified fields are left as-is (partial semantics), and recurring events require a per-occurrence id rather than a series id. It does not spell out that changes are irreversible or what confirm does, but the added context is substantial.

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?

Three tight sentences, front-loaded with the core action before the routing and edge-case caveats. Every sentence earns its place; slightly dense but not padded.

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

Completeness5/5

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

An output schema exists so return values need not be described, and annotations cover the safety profile. Combined with full schema coverage, the description supplies exactly the missing pieces: partial-update semantics and the recurring-occurrence id rule.

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 schema already documents span, notes, title, confirm, dates, and event_id, including the 'empty string to clear' convention and timezone rules. The description restates the partial-update rule and the event_id sourcing, adding little beyond what the schema provides, so the baseline 3 applies.

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?

States a specific verb (Updates), resource (an existing event), and scope (Mac's Calendar.app, by ID). It is immediately distinguishable from create_calendar_event, delete_calendar_event, and the m365_* calendar siblings, which it explicitly routes away from.

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?

Explicit when-to-use guidance: partial-update behavior is stated, the source of event_id is named (list_calendar_events), the recurring-occurrence edge case is called out, and the alternative (m365 calendar tools) is named with its selecting condition.

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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Update Calendar Event

Input Schema

Output Schema

Schema Changelog

TDQS

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