CalDAV MCP Server

Create calendar event

create_event

Creates a new event in a writable iCloud calendar and returns the stored representation without altering existing events. Use list_calendars to obtain calendar_id and update_event for existing events.

Instructions

Create a new event in a writable iCloud calendar and return the stored representation; existing events are not changed. Use list_calendars first to obtain calendar_id, and use update_event when the event already exists. Timed values require matching offsets and timezones, all-day end dates are exclusive, recurrence rules omit the RRULE: prefix, and travel_minutes sets Apple Calendar travel time for timed events.

Input Schema

Name	Required	Description
`end`	Yes	Event end using the same temporal type and timezone as start; an all-day end date is exclusive.
`rrule`	No	RFC 5545 recurrence rule without the RRULE: prefix; defaults to null.
`start`	Yes	Event start as a timed date-time or all-day date.
`alarms`	No	Display reminders; defaults to an empty array.
`summary`	Yes	Event title, between 1 and 1,024 characters.
`location`	No	Event location; defaults to null.
`calendar_id`	Yes	Opaque destination calendar ID returned by list_calendars.
`description`	No	Event notes; defaults to null.
`travel_minutes`	No	Apple Calendar travel time in whole minutes before the start; defaults to null. Only valid for timed events.

Output Schema

Name	Required	Description
`end`	Yes	Normalized event end.
`uid`	Yes	Stored iCalendar UID.
`etag`	Yes	Current ETag for optimistic concurrency, when available.
`href`	Yes	Redacted fingerprint of the CalDAV resource URL.
`rrule`	Yes	Stored RFC 5545 recurrence rule without the RRULE: prefix.
`start`	Yes	Normalized event start.
`alarms`	Yes	Normalized alarms attached to the event.
`summary`	Yes	Stored event title.
`location`	Yes	Stored event location.
`raw_ical`	No	Raw iCalendar resource, included only when explicitly requested.
`recurring`	Yes	Whether this event belongs to a recurring series.
`calendar_id`	Yes	Opaque ID of the containing calendar.
`description`	Yes	Stored event notes.
`resource_id`	Yes	Opaque event ID accepted by get_event, update_event, and delete_event.
`recurrence_id`	Yes	Occurrence identifier for an expanded recurring event.
`travel_minutes`	Yes	Apple Calendar travel time in whole minutes before the start, or null when none is set.
`recurrence_exception`	Yes	Whether this result is an overridden recurrence instance.

Schema Changelog

Changes observed during successful MCP inspections.

Changed3 schema fields changedv0.2.0Oct 25, 2026

addedInput schema / properties / travel_minutes

Added value: +{
+  "anyOf": [
+    {
+      "maximum": 1440,
+      "minimum": 1,
+      "type": "integer"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "default": null,
+  "description": "Apple Calendar travel time in whole minutes before the start; defaults to null. Only valid for timed events."
+}

addedOutput schema / properties / travel_minutes

Added value: +{
+  "anyOf": [
+    {
+      "maximum": 9007199254740991,
+      "minimum": -9007199254740991,
+      "type": "integer"
+    },
+    {
+      "type": "null"
+    }
+  ],
+  "description": "Apple Calendar travel time in whole minutes before the start, or null when none is set."
+}

changedOutput schema / required

Previous value: -[
-  "calendar_id",
-  "resource_id",
-  "uid",
-  "href",
-  "etag",
-  "summary",
-  "start",
-  "end",
-  "description",
-  "location",
-  "rrule",
-  "alarms",
-  "recurring",
-  "recurrence_exception",
-  "recurrence_id"
-]New value: +[
+  "calendar_id",
+  "resource_id",
+  "uid",
+  "href",
+  "etag",
+  "summary",
+  "start",
+  "end",
+  "description",
+  "location",
+  "rrule",
+  "alarms",
+  "travel_minutes",
+  "recurring",
+  "recurrence_exception",
+  "recurrence_id"
+]

Changed14 schema fields changedv0.1.7Sep 5, 2026

removedOutput schema / properties / alarms / items / properties / description / anyOf

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

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

removedOutput schema / properties / alarms / items / properties / uid / anyOf

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

addedOutput schema / properties / alarms / items / properties / uid / type
```
Added value: +[
+  "string",
+  "null"
+]
```

removedOutput schema / properties / description / anyOf

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

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

removedOutput schema / properties / etag / anyOf

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

addedOutput schema / properties / etag / type
```
Added value: +[
+  "string",
+  "null"
+]
```

removedOutput schema / properties / location / anyOf

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

addedOutput schema / properties / location / type
```
Added value: +[
+  "string",
+  "null"
+]
```

removedOutput schema / properties / recurrence_id / anyOf

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

addedOutput schema / properties / recurrence_id / type
```
Added value: +[
+  "string",
+  "null"
+]
```

removedOutput schema / properties / rrule / anyOf

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

addedOutput schema / properties / rrule / type
```
Added value: +[
+  "string",
+  "null"
+]
```

Changed37 schema fields changedv0.1.1Sep 4, 2026

addedInput schema / properties / alarms / description

Added value: +"Display reminders; defaults to an empty array."

addedInput schema / properties / alarms / items / description
```
Added value: +"A display reminder attached to an event."
```
addedInput schema / properties / alarms / items / properties / action / description
```
Added value: +"Alarm action; only DISPLAY is supported."
```
addedInput schema / properties / alarms / items / properties / description / description
```
Added value: +"Optional notification text for this alarm."
```
addedInput schema / properties / alarms / items / properties / minutes_before / description
```
Added value: +"Whole minutes before the event start; use 0 for an alarm at start time."
```

addedInput schema / properties / calendar_id / description

Added value: +"Opaque destination calendar ID returned by list_calendars."

addedInput schema / properties / description / description
```
Added value: +"Event notes; defaults to null."
```

changedInput schema / properties / end / anyOf

Previous value: -[
-  {
-    "additionalProperties": false,
-    "properties": {
-      "date_time": {
-        "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(?:Z|[+-]\\d{2}:\\d{2})$",
-        "type": "string"
-      },
-      "timezone": {
-        "type": "string"
-      }
-    },
-    "required": [
-      "date_time",
-      "timezone"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "properties": {
-      "date": {
-        "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
-        "type": "string"
-      }
-    },
-    "required": [
-      "date"
-    ],
-    "type": "object"
-  }
-]New value: +[
+  {
+    "additionalProperties": false,
+    "description": "A timed calendar value with an explicit offset and IANA timezone.",
+    "properties": {
+      "date_time": {
+        "description": "ISO 8601 date-time with seconds and an explicit UTC offset or Z.",
+        "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(?:Z|[+-]\\d{2}:\\d{2})$",
+        "type": "string"
+      },
+      "timezone": {
+        "description": "IANA timezone for the local event time; its offset must match date_time.",
+        "type": "string"
+      }
+    },
+    "required": [
+      "date_time",
+      "timezone"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "description": "An all-day calendar value.",
+    "properties": {
+      "date": {
+        "description": "Calendar date in YYYY-MM-DD format.",
+        "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
+        "type": "string"
+      }
+    },
+    "required": [
+      "date"
+    ],
+    "type": "object"
+  }
+]

addedInput schema / properties / end / description

Added value: +"Event end using the same temporal type and timezone as start; an all-day end date is exclusive."

addedInput schema / properties / location / description
```
Added value: +"Event location; defaults to null."
```

addedInput schema / properties / rrule / description

Added value: +"RFC 5545 recurrence rule without the RRULE: prefix; defaults to null."

changedInput schema / properties / start / anyOf

Previous value: -[
-  {
-    "additionalProperties": false,
-    "properties": {
-      "date_time": {
-        "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(?:Z|[+-]\\d{2}:\\d{2})$",
-        "type": "string"
-      },
-      "timezone": {
-        "type": "string"
-      }
-    },
-    "required": [
-      "date_time",
-      "timezone"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "properties": {
-      "date": {
-        "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
-        "type": "string"
-      }
-    },
-    "required": [
-      "date"
-    ],
-    "type": "object"
-  }
-]New value: +[
+  {
+    "additionalProperties": false,
+    "description": "A timed calendar value with an explicit offset and IANA timezone.",
+    "properties": {
+      "date_time": {
+        "description": "ISO 8601 date-time with seconds and an explicit UTC offset or Z.",
+        "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(?:Z|[+-]\\d{2}:\\d{2})$",
+        "type": "string"
+      },
+      "timezone": {
+        "description": "IANA timezone for the local event time; its offset must match date_time.",
+        "type": "string"
+      }
+    },
+    "required": [
+      "date_time",
+      "timezone"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "description": "An all-day calendar value.",
+    "properties": {
+      "date": {
+        "description": "Calendar date in YYYY-MM-DD format.",
+        "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
+        "type": "string"
+      }
+    },
+    "required": [
+      "date"
+    ],
+    "type": "object"
+  }
+]

addedInput schema / properties / start / description

Added value: +"Event start as a timed date-time or all-day date."

addedInput schema / properties / summary / description

Added value: +"Event title, between 1 and 1,024 characters."

addedOutput schema / properties / alarms / description

Added value: +"Normalized alarms attached to the event."

addedOutput schema / properties / alarms / items / description

Added value: +"A normalized alarm returned by iCloud Calendar."

addedOutput schema / properties / alarms / items / properties / action / description
```
Added value: +"Stored iCalendar alarm action."
```
addedOutput schema / properties / alarms / items / properties / description / description
```
Added value: +"Stored alarm notification text, when available."
```
addedOutput schema / properties / alarms / items / properties / minutes_before / description
```
Added value: +"Whole minutes before event start, when representable."
```
addedOutput schema / properties / alarms / items / properties / uid / description
```
Added value: +"Stored alarm UID, when available."
```
addedOutput schema / properties / calendar_id / description
```
Added value: +"Opaque ID of the containing calendar."
```
addedOutput schema / properties / description / description
```
Added value: +"Stored event notes."
```

changedOutput schema / properties / end / anyOf

Previous value: -[
-  {
-    "additionalProperties": false,
-    "properties": {
-      "date_time": {
-        "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(?:Z|[+-]\\d{2}:\\d{2})$",
-        "type": "string"
-      },
-      "timezone": {
-        "maxLength": 4096,
-        "minLength": 1,
-        "type": "string"
-      }
-    },
-    "required": [
-      "date_time",
-      "timezone"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "properties": {
-      "date": {
-        "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
-        "type": "string"
-      }
-    },
-    "required": [
-      "date"
-    ],
-    "type": "object"
-  }
-]New value: +[
+  {
+    "additionalProperties": false,
+    "description": "A stored timed calendar value.",
+    "properties": {
+      "date_time": {
+        "description": "Stored ISO 8601 date-time with seconds and an explicit UTC offset or Z.",
+        "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(?:Z|[+-]\\d{2}:\\d{2})$",
+        "type": "string"
+      },
+      "timezone": {
+        "description": "IANA timezone associated with the stored date-time.",
+        "maxLength": 4096,
+        "minLength": 1,
+        "type": "string"
+      }
+    },
+    "required": [
+      "date_time",
+      "timezone"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "description": "An all-day calendar value.",
+    "properties": {
+      "date": {
+        "description": "Calendar date in YYYY-MM-DD format.",
+        "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
+        "type": "string"
+      }
+    },
+    "required": [
+      "date"
+    ],
+    "type": "object"
+  }
+]

addedOutput schema / properties / end / description
```
Added value: +"Normalized event end."
```

addedOutput schema / properties / etag / description

Added value: +"Current ETag for optimistic concurrency, when available."

addedOutput schema / properties / href / description

Added value: +"Redacted fingerprint of the CalDAV resource URL."

addedOutput schema / properties / location / description
```
Added value: +"Stored event location."
```

addedOutput schema / properties / raw_ical / description

Added value: +"Raw iCalendar resource, included only when explicitly requested."

addedOutput schema / properties / recurrence_exception / description

Added value: +"Whether this result is an overridden recurrence instance."

addedOutput schema / properties / recurrence_id / description

Added value: +"Occurrence identifier for an expanded recurring event."

addedOutput schema / properties / recurring / description

Added value: +"Whether this event belongs to a recurring series."

addedOutput schema / properties / resource_id / description

Added value: +"Opaque event ID accepted by get_event, update_event, and delete_event."

addedOutput schema / properties / rrule / description

Added value: +"Stored RFC 5545 recurrence rule without the RRULE: prefix."

changedOutput schema / properties / start / anyOf

Previous value: -[
-  {
-    "additionalProperties": false,
-    "properties": {
-      "date_time": {
-        "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(?:Z|[+-]\\d{2}:\\d{2})$",
-        "type": "string"
-      },
-      "timezone": {
-        "maxLength": 4096,
-        "minLength": 1,
-        "type": "string"
-      }
-    },
-    "required": [
-      "date_time",
-      "timezone"
-    ],
-    "type": "object"
-  },
-  {
-    "additionalProperties": false,
-    "properties": {
-      "date": {
-        "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
-        "type": "string"
-      }
-    },
-    "required": [
-      "date"
-    ],
-    "type": "object"
-  }
-]New value: +[
+  {
+    "additionalProperties": false,
+    "description": "A stored timed calendar value.",
+    "properties": {
+      "date_time": {
+        "description": "Stored ISO 8601 date-time with seconds and an explicit UTC offset or Z.",
+        "pattern": "^\\d{4}-\\d{2}-\\d{2}T\\d{2}:\\d{2}:\\d{2}(?:Z|[+-]\\d{2}:\\d{2})$",
+        "type": "string"
+      },
+      "timezone": {
+        "description": "IANA timezone associated with the stored date-time.",
+        "maxLength": 4096,
+        "minLength": 1,
+        "type": "string"
+      }
+    },
+    "required": [
+      "date_time",
+      "timezone"
+    ],
+    "type": "object"
+  },
+  {
+    "additionalProperties": false,
+    "description": "An all-day calendar value.",
+    "properties": {
+      "date": {
+        "description": "Calendar date in YYYY-MM-DD format.",
+        "pattern": "^\\d{4}-\\d{2}-\\d{2}$",
+        "type": "string"
+      }
+    },
+    "required": [
+      "date"
+    ],
+    "type": "object"
+  }
+]

addedOutput schema / properties / start / description
```
Added value: +"Normalized event start."
```
addedOutput schema / properties / summary / description
```
Added value: +"Stored event title."
```
addedOutput schema / properties / uid / description
```
Added value: +"Stored iCalendar UID."
```

First observedv0.1.0Sep 4, 2026

TDQS

A4.5/5.0

Behavior4/5

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

Annotations already establish that this is a non-read-only, non-idempotent, open-world, non-destructive operation. The description adds useful behavioral context: it writes to a writable iCloud calendar, returns the stored representation, and explicitly states existing events are not changed. It omits permission and rate-limit details, but the annotation coverage lowers the burden.

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?

The description is front-loaded with purpose and usage, then consolidates key temporal and recurrence constraints without wasted text. Every clause carries actionable meaning for invocation.

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?

Given a nine-parameter create tool with full schema coverage, annotations, and an output schema, the description covers purpose, prerequisites, alternatives, and critical formatting semantics. Nothing essential for correct invocation is missing.

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%, and the schema already documents matching timezone offsets, exclusive all-day end dates, the RRULE prefix omission, and travel_minutes being valid only for timed events. The description repeats and emphasizes these constraints but adds little genuinely new parameter-level meaning beyond the schema.

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: create a new event in a writable iCloud calendar. It also clarifies that it returns the stored representation and does not modify existing events, which distinguishes it from update_event and other sibling tools.

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?

Explicitly directs the agent to call list_calendars first to obtain calendar_id, and names update_event as the alternative when the event already exists. This gives clear prerequisites and a concrete routing rule.

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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