List Calendars

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

Annotations already declare readOnlyHint=true, so the read-only nature is known. The description adds the scope that these are calendars 'available to the helper app', which provides useful context about what will be listed. It does not mention return format or pagination, but this is acceptable given the simplicity and existing annotation coverage.

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, well-formed sentence that immediately states the action and resource. Every word adds value, with no fluff or repetition.

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 extremely simple nature of the tool (no parameters, read-only, no output schema), the description is fully sufficient. It clearly states what the tool does without needing to elaborate on return values or side effects.

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 the baseline is 4 per the rubric. The description does not need to elaborate on parameter semantics as there are none.

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 clearly states the tool lists event calendars available to the helper app, using a specific verb ('List') and resource ('event calendars'). It is distinct from sibling tools like calendar_list_events which lists events, and calendar_get_event which fetches a single event.

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: it is the way to discover which calendars exist before performing other calendar operations. However, it does not explicitly state when to use it versus alternatives or provide exclusions, so it relies on the obviousness of the sibling tool set.

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