When the calendar is busy

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

Beyond the annotations, the description adds meaningful behavioral context: the response contains only start/end times, no titles or attendees, and notably 'nothing anybody else wrote comes back, so there is no untrusted content in the answer at all.' This explains privacy and content-filtering behavior that annotations do not cover.

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?

Two front-loaded sentences with no wasted words. The core behavior is stated first, followed by the differentiating use-case rationale. Every phrase 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?

Given the rich annotations, complete input schema, and the presence of an output schema, the description adds the needed selection-level context: what the tool returns, what it omits, and why it is safe to use for free/busy checks. Nothing essential for correct selection or invocation is 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?

Schema description coverage is 100%, so the parameters are fully documented in the schema. The tool description adds no additional parameter-level meaning, which aligns with the baseline of 3.

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 that the tool returns busy periods in a time range, with the specific behavioral scoping of 'start and end only'. It differentiates itself from sibling calendar tools by emphasizing that no titles or attendees are returned, making its purpose distinct from list_events, search_events, and get_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 clearly frames when to use the tool: 'when am I free' and when a data-sparing, untrusted-content-free answer is desired. It implies exclusion of use cases needing titles or attendees, but does not explicitly name an alternative sibling tool for those cases.

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