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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds real context beyond them: a hard 62-day range cap, timezone-of-choice output, and per-host filtering for round-robin types. It doesn't describe the shape of returned slots (e.g., count/density), so not a 5.

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?

Three short sentences, front-loaded with the core capability, then the round-robin caveat, then the next-step pointer. No filler.

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 read-only finder with no output schema, the definition covers inputs, limits, and timezone behavior well. It leaves the returned slot format implicit, a minor gap against the complexity of the call.

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 coverage is 67%, and the description adds the 62-day from/to constraint that the schema does not encode, plus clarifies why host matters (round-robin only that host's times). It doesn't elaborate on the person/meeting_type slug composition beyond what the schema says.

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 (free start times for a meeting type) plus the date scope and timezone behavior. The round-robin host clause and the 'Book one with calendar_book' pointer clearly distinguish it from calendar_book and calendar_list_meeting_types.

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 routes the follow-up action to calendar_book and clarifies the round-robin case. It doesn't state when not to use it or point to calendar_list_meeting_types as the way to obtain a meeting_type slug, so usage is clear but not fully closed.

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