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lukegskw

CalDAV MCP Server

by lukegskw
OverviewSchemaRelated ServersScoreDiscussions(2)
TypeScript
Remote

List calendars

list_calendars
Read-onlyIdempotent

List all calendars from the configured iCloud account. Obtain the calendar_id required for creating or listing events.

Instructions

List calendars available in the configured iCloud account. Use this first to obtain the opaque calendar_id required by list_events and create_event; writable is a best-effort capability indicator.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault

No arguments

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
calendarsYesCalendars available to the configured account.

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. Changed6 schema fields changedv0.1.7
    • removedOutput schema / properties / calendars / items / properties / description / anyOf
      Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
    • addedOutput schema / properties / calendars / items / properties / description / type
      Added value: +[
+  "string",
+  "null"
+]
    • removedOutput schema / properties / calendars / items / properties / timezone / anyOf
      Removed value: -[
-  {
-    "type": "string"
-  },
-  {
-    "type": "null"
-  }
-]
    • addedOutput schema / properties / calendars / items / properties / timezone / type
      Added value: +[
+  "string",
+  "null"
+]
    • removedOutput schema / properties / calendars / items / properties / writable / anyOf
      Removed value: -[
-  {
-    "type": "boolean"
-  },
-  {
-    "type": "null"
-  }
-]
    • addedOutput schema / properties / calendars / items / properties / writable / type
      Added value: +[
+  "boolean",
+  "null"
+]
  2. Changed6 schema fields changedv0.1.1
    • addedOutput schema / properties / calendars / description
      Added value: +"Calendars available to the configured account."
    • addedOutput schema / properties / calendars / items / properties / calendar_id / description
      Added value: +"Opaque calendar ID used by event tools."
    • addedOutput schema / properties / calendars / items / properties / description / description
      Added value: +"Calendar description."
    • addedOutput schema / properties / calendars / items / properties / display_name / description
      Added value: +"Calendar display name."
    • addedOutput schema / properties / calendars / items / properties / timezone / description
      Added value: +"Calendar timezone, when advertised by the server."
    • addedOutput schema / properties / calendars / items / properties / writable / description
      Added value: +"Best-effort writable status; null means unknown."
  3. First observedv0.1.0

TDQS

A4.9/5.0
Behavior5/5

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

The annotations already establish read-only, idempotent, and non-destructive behavior, and the description adds meaningful context: the writable field is only a best-effort capability indicator, and calendar IDs are opaque. This helps the agent avoid over-trusting the writable flag and treating IDs as human-readable.

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 two concise sentences with no filler. It leads with the core function and then adds the most important usage detail, making it easy to scan and act on.

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 that the tool takes no parameters, has a rich set of annotations, and has an output schema, the description covers all necessary context: what is being listed, the account scope, the purpose of the returned IDs, and the reliability of the writable indicator.

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?

The input schema has no parameters, so the baseline for this dimension is 4. The description does not need to explain any parameter semantics because there are none.

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 clearly states that this tool lists calendars in the configured iCloud account, using a specific verb and resource. It also distinguishes itself from the sibling event tools by explaining that it provides the calendar_id needed by list_events and create_event.

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?

It explicitly instructs the agent to use this tool first in order to obtain the opaque calendar_id required by event operations. This gives clear sequencing guidance and explains the purpose of the tool relative to its siblings.

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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