calendar_list_calendars

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

No annotations are provided, so the description carries the burden. It is a zero-parameter read-only lister, and the description does disclose that the response includes writability information, which is the key behavioral detail. It does not state read-only nature or whether any calendar types (shared, subscribed) are omitted, leaving modest gaps.

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?

A single front-loaded sentence with the action first and the payoff last; every clause earns its place.

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-param, no-annotation tool with no output schema, the description supplies both the action and the shape of the useful return field (writability). It is sufficient to select and call the tool; only edge cases about what calendars are excluded are missing.

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?

The tool takes no parameters, so the baseline of 4 applies. There is nothing for the description to clarify beyond the return content it already mentions.

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?

States a specific verb+resource ('List the calendars in Calendar.app') and adds what the result contains ('with their writability'), so it is clearly a discovery tool. It does not explicitly name a sibling it is distinct from, but its purpose is unambiguous against calendar_upcoming/calendar_week/calendar_add.

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?

The clause 'so events land on the intended calendar instead of the default' gives a concrete motivating context: call this before choosing a calendar for an event. No explicit exclusions or alternatives are named, so it stops short of a 5.

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