Chronary

update_event

Idempotent

Reschedule or edit an event — change its title, description, start/end times, location, status, reminders, or metadata. Use this to move an appointment to a new time or update its details. Provide only the fields you want to change. Holds cannot be edited via this tool (use confirm_event / release_event). External iCal events are read-only. calendar_id is optional — if omitted it is resolved from the 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": {
      "event_id": "<event_id>"
    },
    "name": "update_event"
  }
}

Input Schema

Name	Required	Description
`title`	No	New event title
`status`	No	New event status
`all_day`	No	Whether this is an all-day event
`end_time`	No	New end time (ISO 8601)
`event_id`	Yes	Event ID to update
`metadata`	No	Replacement metadata object
`reminders`	No	Reminder offsets in minutes before start_time. Omit to leave unchanged, null to inherit the calendar default, [] for no reminders.
`start_time`	No	New start time (ISO 8601)
`calendar_id`	No	Calendar ID that owns the event. Optional — if omitted the calendar is resolved from the event.
`description`	No	New description, or null to clear it
`recurrence_rule`	No	Set/change the recurring series rule (RFC 5545 RRULE subset, full-series semantics), or null to make the event a one-off. Changing the rule or start_time resets cancelled occurrences.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedNov 10, 2026

addedInput schema / properties / description / anyOf

Added value: +[
+  {
+    "maxLength": 10000,
+    "type": "string"
+  },
+  {
+    "type": "null"
+  }
+]

removedInput schema / properties / description / type
```
Removed value: -[
-  "string",
-  "null"
-]
```

Changed4 schema fields changedSep 29, 2026

removedInput schema / properties / description / anyOf

Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]

addedInput schema / properties / description / type
```
Added value: +[
+  "string",
+  "null"
+]
```

changedInput schema / properties / end_time / pattern

Previous value: -"^(?:(?:\\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])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d(?::[0-5]\\d(?:\\.\\d+)?)?(?:Z))$"New value: +"^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d:[0-5]\\d(?:\\.\\d+)?(?:Z))$"

changedInput schema / properties / start_time / pattern

Previous value: -"^(?:(?:\\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])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d(?::[0-5]\\d(?:\\.\\d+)?)?(?:Z))$"New value: +"^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d:[0-5]\\d(?:\\.\\d+)?(?:Z))$"

Changed1 schema field changedJul 11, 2026

addedInput schema / properties / recurrence_rule

Added value: +{
+  "anyOf": [
+    {
+      "maxLength": 256,
+      "type": "string"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "description": "Set/change the recurring series rule (RFC 5545 RRULE subset, full-series semantics), or null to make the event a one-off. Changing the rule or start_time resets cancelled occurrences."
+}

First observedJul 8, 2026

TDQS

A4.5/5.0

Behavior4/5

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

Annotations already declare the mutation profile (readOnly=false, idempotent=true, destructive=false), and the description adds real constraints beyond them: holds are out of scope, external iCal events are read-only, and calendar_id can be resolved automatically. It stops short of stating what the call returns or what happens to occurrences when a series is edited (that detail lives only in the schema).

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 and followed by exclusions. Nearly every clause earns its place; the only wasted/incorrect content is the 'location' mention that has no matching parameter.

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 an 11-parameter mutation tool with nested metadata and no output schema, the description covers scope, exclusions, and update semantics adequately. The gaps are secondary details already carried by parameter descriptions (recurrence reset behavior, reminder null/[] semantics) and the unstated return value.

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 baseline is 3, but the description adds patch semantics ('provide only the fields you want to change') and explains the calendar_id fallback. Minor defect: it advertises 'location' as editable although no location property exists in the schema, which could mislead an agent into expecting that field.

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?

Opens with a specific verb pair and resource ('Reschedule or edit an event') and enumerates the mutable fields. It also names the sibling tools it is not (confirm_event / release_event) and the class of events it cannot touch (external iCal), so an agent can distinguish it from neighbors without opening a schema.

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 ('move an appointment to a new time or update its details'), explicit partial-update instruction ('Provide only the fields you want to change'), and explicit exclusions with alternatives ('Holds cannot be edited via this tool (use confirm_event / release_event)'). Little 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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