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

No annotations are provided, so the description carries the burden. It adds a meaningful behavioral guarantee—returns times only, never event titles—but it does not disclose auth/permission needs, timezone assumptions, or what happens when no time range is supplied.

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 concise sentences with the core behavior first and the privacy-relevant limitation second. Every clause earns its place; no filler or duplicated schema content.

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?

Reasonable for a simple query tool: it states the result type, multi-calendar scope, and privacy guarantee. However, with no output schema and no annotations, it should say more about required/optional time bounds and the shape of the returned busy blocks to be fully self-sufficient.

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 only 50%: mailbox and calendarIds are documented, but timeMin and timeMax have no descriptions. The description reinforces the multi-calendar behavior and output concept but does not explain the time-range parameters or their format, so it does not compensate for the gap.

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 action and scope: returning busy blocks across one or more Google Calendars to enable proposing a free slot. The explicit 'never event titles' distinguishes it from event-listing/search tools, and the Google-specific naming separates it from the Outlook variant.

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?

Gives clear context for when it is useful: when proposing a free slot. It does not explicitly name alternatives or exclusions, but the purpose and privacy constraint make the intended scenario unmistakable.

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