Find free time

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

Annotations already declare readOnlyHint and idempotentHint, but the description adds crucial behavior beyond them: if any calendar is unreadable, NO slots are returned and 'incomplete' is set, preventing double-bookings. It also discloses the timezone default-and-echo behavior, which is valuable operational context.

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?

The description is three sentences with no filler: the first states the core function, the second gives hard input constraints, and the third highlights a critical safety behavior. The IMPORTANT warning is front-loaded enough to prevent misuse.

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?

The description covers core behavior, defaults, working-hours constraints, and failure semantics, while parameter details are fully present in the schema. The only meaningful omission is a precise description of the successful output structure beyond 'gaps' and 'incomplete,' but the annotation suite and schema make this a fairly complete definition.

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 baseline is 3. The description adds value beyond the schema by emphasizing that time_min/time_max must carry an explicit UTC offset and by revealing the timezone default (server zone) plus the echo behavior, which the schema does not specify.

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 opens with a precise verb+resource combination: find gaps that are free on EVERY account within working hours. This clearly differentiates the tool from event-listing siblings like calendar_list_events or calendar_get_event by emphasizing cross-account availability search.

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 implies when to use the tool: when you need common free time across multiple accounts within working hours. It does not explicitly name an alternative or state a when-not-to-use condition, but the context is strong enough for an agent to select it over the event-centric calendar siblings.

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