Agent Mail Gateway

Change a meeting you created

update_event

Change a meeting created with create_event: give only the fields that change (null removes location or description_markdown).

Instructions

Change a meeting created with create_event: give only the fields that change (null removes location or description_markdown). Attendees get an updated invitation that replaces the old entry in their calendar; removed attendees get a cancellation. Changing the time clears earlier answers; changing only start keeps the duration. Returns the updated event.

Input Schema

TableJSON Schema

Name	Required	Description
`id`	Yes	Event id from create_event or list_events
`end`	No	End, same format as start and after it; for all_day the last day (inclusive, defaults to start)
`start`	No	Start, e.g. 2026-10-05T14:00 (mailbox time zone) or with offset/Z; for all_day a date like 2026-10-05
`title`	No	Meeting title shown in calendars
`all_day`	No	true: all-day event over whole days; start and end are dates. Default false
`show_as`	No	How the time shows in attendees' calendars: busy (default), free, tentative or oof (out of office)
`location`	No	Place or meeting link; null removes it
`timezone`	No	IANA zone for times without offset; defaults to the mailbox timezone
`attendees`	No	Email addresses to invite; each must be on allow_send_to
`description_markdown`	No	Agenda or notes in Markdown; null removes them

Schema Changelog

Changes observed during successful MCP inspections.

Changed10 schema fields changedv0.5.0Oct 22, 2026

addedInput schema / properties / all_day

Added value: +{
+  "description": "true: all-day event over whole days; start and end are dates. Default false",
+  "type": "boolean"
+}

addedInput schema / properties / end / anyOf

Added value: +[
+  {
+    "format": "date",
+    "pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))$",
+    "type": "string"
+  },
+  {
+    "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}(:\\d{2}(\\.\\d+)?)?(Z|[+-]\\d{2}:\\d{2})?$",
+    "type": "string"
+  }
+]

changedInput schema / properties / end / description

Previous value: -"End, same format as start; must be after start"New value: +"End, same format as start and after it; for all_day the last day (inclusive, defaults to start)"

removedInput schema / properties / end / pattern

Removed value: -"^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}(:\\d{2}(\\.\\d+)?)?(Z|[+-]\\d{2}:\\d{2})?$"

removedInput schema / properties / end / type
```
Removed value: -"string"
```

addedInput schema / properties / show_as

Added value: +{
+  "description": "How the time shows in attendees' calendars: busy (default), free, tentative or oof (out of office)",
+  "enum": [
+    "busy",
+    "free",
+    "tentative",
+    "oof"
+  ],
+  "type": "string"
+}

addedInput schema / properties / start / anyOf

Added value: +[
+  {
+    "format": "date",
+    "pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))$",
+    "type": "string"
+  },
+  {
+    "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}(:\\d{2}(\\.\\d+)?)?(Z|[+-]\\d{2}:\\d{2})?$",
+    "type": "string"
+  }
+]

changedInput schema / properties / start / description

Previous value: -"Start, e.g. 2026-10-05T14:00 (mailbox time zone) or with offset/Z"New value: +"Start, e.g. 2026-10-05T14:00 (mailbox time zone) or with offset/Z; for all_day a date like 2026-10-05"

removedInput schema / properties / start / pattern

Removed value: -"^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}(:\\d{2}(\\.\\d+)?)?(Z|[+-]\\d{2}:\\d{2})?$"

removedInput schema / properties / start / type
```
Removed value: -"string"
```

Changed8 schema fields changedv0.3.4Oct 5, 2026

addedInput schema / properties / description_markdown / anyOf

Added value: +[
+  {
+    "maxLength": 512000,
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]

changedInput schema / properties / description_markdown / description

Previous value: -"Agenda or notes in Markdown"New value: +"Agenda or notes in Markdown; null removes them"

removedInput schema / properties / description_markdown / maxLength
```
Removed value: -512000
```
removedInput schema / properties / description_markdown / type
```
Removed value: -"string"
```

addedInput schema / properties / location / anyOf

Added value: +[
+  {
+    "maxLength": 500,
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]

changedInput schema / properties / location / description

Previous value: -"Place or meeting link"New value: +"Place or meeting link; null removes it"

removedInput schema / properties / location / maxLength
```
Removed value: -500
```
removedInput schema / properties / location / type
```
Removed value: -"string"
```

Changed8 schema fields changedv0.3.2Oct 3, 2026
- addedInput schema / properties / attendees / description
```
Added value: +"Email addresses to invite; each must be on allow_send_to"
```
- addedInput schema / properties / description_markdown / description
```
Added value: +"Agenda or notes in Markdown"
```
- addedInput schema / properties / description_markdown / maxLength
```
Added value: +512000
```
- addedInput schema / properties / end / description
```
Added value: +"End, same format as start; must be after start"
```
- addedInput schema / properties / id / description
```
Added value: +"Event id from create_event or list_events"
```
- addedInput schema / properties / location / description
```
Added value: +"Place or meeting link"
```
- addedInput schema / properties / start / description
```
Added value: +"Start, e.g. 2026-10-05T14:00 (mailbox time zone) or with offset/Z"
```
- addedInput schema / properties / title / description
```
Added value: +"Meeting title shown in calendars"
```
First observedv0.1.0Oct 2, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Goes well beyond the annotations: it discloses that attendees receive a replacement invitation, removed attendees get a cancellation, time changes clear prior responses, and start-only changes preserve duration. These downstream side effects are exactly what an agent cannot derive from readOnlyHint=false and destructiveHint=false.

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

Conciseness5/5

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

Three dense sentences, front-loaded with the partial-update rule and its null convention, then side effects, then the timing rule. Every clause carries decision-relevant information and none repeats the schema.

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?

Covers mutation semantics, null-removal behavior, attendee notification effects, and the return value ('Returns the updated event') despite there being no output schema. The 10-parameter, mutation-heavy surface is adequately explained alongside full schema coverage.

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 100%, so the baseline is 3, but the description adds real semantics on top: null explicitly removes location or description_markdown, and changing only start preserves duration. It does not touch the other parameters (attendees, all_day, show_as, timezone), so it is not fully comprehensive.

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 and resource ('Change a meeting created with create_event') and defines the update as a partial/patch operation. This makes it clearly distinct from create_event, cancel_event, and get_event in the sibling set without any inference by the agent.

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

Usage Guidelines4/5

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

'give only the fields that change' explicitly tells the agent to send a patch payload rather than a full object, which is the key usage decision for an update tool. It anchors usage to events made with create_event but does not name when to use a sibling instead (e.g., cancel_event for cancellation).

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

Deploy Server

Change a meeting you created

Instructions

Input Schema

Schema Changelog

TDQS

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