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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds that results are comparative (metrics measured against category peers), which is genuinely useful context, but it says nothing about freshness windows, default 90-day range, diagnostics, or pagination behavior.

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 verb and resource first, then scope and payload. No filler, though the long metric enumeration could be trimmed since the schema already exposes those columns.

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 annotations covering the safety profile, 100% param coverage, and an output schema handling return values, the remaining burden is modest. The description supplies the domain framing (Brand Metrics share-of-voice vs category peers) that the schema cannot; only usage routing to sibling tools 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% across all 13 parameters, so defaults, bounds, LIKE-match semantics and the sort enum are fully documented in the schema. The description's metric list loosely maps to the sort_by enum but adds no syntax or format detail beyond what the schema already provides.

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 (Get) and a clearly bounded resource (Amazon Ads Brand Metrics share-of-voice signals), then enumerates the exact metric families returned (awareness, consideration, sales, branded searches, detail-page views, add-to-carts, brand customers) and the comparative framing vs category peers. This is enough to separate it from siblings like get_brand_health or get_brand_search_terms, though it never names an adjacent tool.

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 never says when to reach for this tool versus the many neighboring brand/ads tools (get_brand_health, get_brand_search_terms, get_search_query_performance), nor any preconditions. Usage is only inferable from the metric list, which is thin guidance.

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