list_calendars

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

With no annotations, the description carries the transparency burden and largely meets it by clearly indicating read-only listing behavior and detailing the return contract: name, provider, url, description, timezone, and supported_components. It does not explicitly mention side-effect-freedom, authentication, or pagination, but for a simple parameterless list operation these omissions are minor.

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

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

The description is front-loaded with a single-sentence purpose followed by a compact bulleted return list. Every line adds concrete, non-redundant information, making it easy for an agent to parse quickly.

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

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

For a zero-parameter listing tool with an output schema indicated, the description is fully sufficient: it states the resource, the scope, and the complete metadata shape. An agent can invoke it with no inputs and interpret the results without needing additional context.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

This tool has zero parameters and an empty input schema, so there is no parameter detail for the description to clarify. The phrase 'all available' reinforces that no filters are needed, and the parameterless baseline of 4 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('List') and a clear resource ('all available iCloud calendars') while signaling the return of comprehensive metadata. This cleanly distinguishes it from event-focused siblings like list_events and adds context beyond the tool name alone.

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

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

No explicit when-to-use guidance or named alternatives are provided. The scope 'all available iCloud calendars' implies this is the calendar-discovery/listing operation, and the sibling list_events is naturally differentiated by resource type, but the description does not explicitly say when to choose this over another tool.

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