calendar_get_free_busy

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

Beyond the readOnlyHint annotation, the description adds crucial behavioral context: it does not reveal meeting details ('without seeing what their meetings are'), returns specific availability categories (busy periods, slot-by-slot free/tentative/busy/out of office), and states the required permission (Calendars.ReadBasic). This significantly enhances the agent's understanding.

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 sentences, front-loaded with the primary action and scope, then a clear alternative and permission note. Every sentence contributes value with no redundancy or fluff.

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 moderately complex tool with no output schema, the description adequately discloses return value structure (per-person busy periods and slot breakdown), required permissions, and tool-specific semantics (doesn't reveal meeting details). Together with the strong annotations, this gives the agent a complete picture.

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% for all 5 parameters, so the schema already documents each field. The description adds context about the output shape (slot-by-slot breakdown) which indirectly relates to interval_minutes, but it does not explain individual parameters beyond the schema. Baseline 3 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 ('Look up whether people are free or busy') and resource, clarifying it's a read-only availability check. It also distinguishes from the sibling tool calendar_find_meeting_times by explicitly stating the difference in use case.

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?

Explicitly states when to use: 'Use to answer "when is X available"' and provides an alternative: 'calendar_find_meeting_times is better when the goal is a slot that suits a whole group.' This clearly guides tool selection.

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