calendar_find_free_slots

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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint, so the safety profile is covered. The description adds real behavioral context beyond that: which events count as busy (non-free, non-cancelled), the selected-calendar scoping, the no-working-hours inference boundary, and the required 'calendar' permission.

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 tightly written clauses with the core action front-loaded and no filler; the version/permission suffix is the only low-value element.

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 values need no explanation, and annotations carry the safety profile. The description covers boundaries and scope well; the only gap is the unaddressed durationMinutes/timezone semantics for a 5-param tool.

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 60%. The description maps loosely to parameters ('requested range' → start/end, 'selected calendars' → calendarIds), but durationMinutes has an empty schema description and no compensating explanation, and timezone semantics are unaddressed. Baseline 3 for partial coverage that is only marginally compensated.

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 ('Find free intervals') and clarifies the computation basis ('using non-free, non-cancelled calendar events'). This clearly distinguishes it from siblings like calendar_list_events, though it does not name an alternative explicitly.

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 clause 'does not infer working hours' and 'Bound to selected calendars' give boundary conditions that imply the intended usage context, but there is no explicit when-to-use/when-not guidance or routing to sibling tools such as calendar_list_events.

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