calendar_list_calendars

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

No annotations are provided, so the description must carry the burden. It conveys that the tool is a read-only operation and that only calendars the user has access to are included. However, it does not disclose potential behavioral details like output structure or pagination. The qualifier 'has access to' adds useful context, but more could be said about return format.

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 a single concise sentence that conveys the essential purpose without any fluff. Every word adds meaning, and the sentence structure is clear and front-loaded.

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?

Given the tool's simplicity (no parameters, no nested objects) and the presence of an output schema, the description is largely sufficient. It clearly defines what the tool does and its scope. It doesn't mention alternatives, but that's a minor omission for a basic listing operation.

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 has zero parameters, so per the rubric, the baseline is 4. The description adds no parameter information, but none is needed. The schema is empty and fully covered, so there is no gap.

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 precisely states the action ('List all calendars') and the scope ('the user has access to'). It is unambiguous and distinguishes itself from sibling tools like calendar_get_events, which focus on events rather than calendar metadata.

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 description implies usage: to retrieve a list of accessible calendars. However, it does not explicitly state when to use it over alternatives, nor does it mention any exclusions or prerequisites. For a simple listing tool, the implication is clear enough, but it lacks direct guidance.

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