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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld). The description adds genuine context the annotations cannot: meeting duration, platform, and the 30-day availability window. It still omits whether slots reflect real-time calendar state or caching, and whether the timeZone parameter shifts the returned slot values.

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 short sentences, zero filler, with the business constraints front-loaded and the follow-up action last. Nothing could be removed without losing information.

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?

An output schema exists, so return format needn't be explained, and the description covers scope plus the handoff to book_call. Minor gap: it doesn't state whether an empty result is possible or how the returned times relate to the caller's timeZone.

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% and both parameters (lang, timeZone) are fully documented with defaults, enums, and examples. The description adds no parameter-level detail, so baseline 3 applies — the schema carries all the weight.

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 the resource precisely: free 30-minute intro-call slots on Google Meet within a 30-day horizon. That scope is specific enough to separate it from every read-only sibling, though the verb ('returns/lists') is implied rather than written.

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 closes the loop with book_call ('Pass one as start to book_call'), which tells the agent exactly what to do with the output. No when-not-to-use guidance is needed here since no sibling competes for this job, but it never says what to do if no slots are returned.

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