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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds real behavioral context beyond them: results are anonymized to time plus member identifier, and titles are explicitly excluded, which tells the agent what it will and will not receive. It stops short of describing ordering, limits, or whether all-day/recurring events are expanded.

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?

A single front-loaded sentence with the resource, the privacy constraint, and the scoping all in place. The parenthetical '(time + member only, never titles)' earns its space by preempting a likely wrong assumption, and there is 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 three-parameter read-only lookup with full schema coverage and complete safety annotations, the description covers what the tool returns and the privacy limit, which is what an agent most needs. Gaps are minor: no mention of result ordering, maximum range, or how it relates to the free-window/schedule-conflict siblings.

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%, with both date fields documented as ISO YYYY-MM-DD and member_ids documented as optional with 'omit for the whole household'. The description only restates date range and member scoping, adding no format or edge-case detail beyond the schema, so the baseline of 3 applies.

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 and resource ('List generic busy intervals') and pins the output scope ('time + member only, never titles') plus the input scope (date range, household members). It is clear what the tool returns, though it does not name a sibling such as get_free_windows or get_schedule_conflicts to establish the boundary between them.

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?

Usage is only implied: an agent can infer you call this to see when members are occupied, and 'never titles' hints at a privacy-preserving availability view. There is no explicit when-to-use/when-not guidance and no pointer to the complementary availability tool, so selection between siblings is left to inference.

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