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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuinely non-structured context: 'Estimates are coarse 0-100 comparisons, not measurements,' which tells the agent to qualify the output, plus the default ordering behavior. It does not describe the response shape, but the output schema carries that.

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 sentences, front-loaded with the usage trigger, then output scope, then the precision caveat. No filler or restated title. Slightly dense in the trigger clause but every sentence earns its place.

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?

With an output schema present, return-value detail is not the description's job, and annotations cover the safety profile. The description supplies the trigger conditions, default ordering, and the coarse-estimate caveat, which is enough for correct invocation. It is not exhaustive — no note on how many areas may be passed together or how ties are handled — but nothing essential is missing.

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 schema already documents sort_by and placements, and the baseline is 3. The description reinforces defaults ('ordered by fade by default', 'or the ones requested') but adds no syntax or semantics beyond what the schema states. Minor note: 'stretch or curvature' are offered as comparison topics yet are absent from the sort_by enum, leaving a small ambiguity the description does not resolve.

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 (compare) and resource (body areas/placements), and discloses the output scope: 'Returns the ten common areas (or the ones requested), ordered by fade by default.' No sibling (assess_tattoo_idea, check_line_spacing, get_pre_booking_checklist, get_tattoo_size_chart) covers cross-area comparison, and the description makes that scope legible without opening the schema.

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?

Opens with an explicit trigger list: 'Use when the user asks how body areas compare for pain, fading, sun, friction, stretch or curvature, or which areas hold ink longest.' That maps well onto the sort_by enum and routes the agent correctly. It stops short of naming when not to use it or pointing to an alternative sibling, so it is clear context rather than full routing guidance.

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