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

Annotations already declare readOnlyHint and openWorldHint, so the description's real contribution is the explicit "Costs 4 credits" disclosure, which no structured field carries and which matters for a paid, live-data call. It does not cover freshness or whether difficulty is per-store, but the credit cost is a substantial addition beyond annotations.

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 short sentences: what it returns, what it's for, what it costs. Front-loaded with the resource and metric list, and 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 no output schema, the description does the right thing by naming the returned metrics, and it covers the credit cost. It stops short of explaining the scale or meaning of "difficulty" and whether "languages" is a per-language breakdown, which leaves a small gap for interpreting results.

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 store enum values and country/keyword formats fully documented in the schema itself. The description adds no parameter-level meaning beyond that, so the baseline 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 ("Get the ASO profile of a keyword") and enumerates the three returned metrics (SAP, difficulty, languages), which implicitly distinguishes it from the narrower siblings keyword_metrics_sap and keyword_metrics_volatility. It never names those siblings explicitly, so the differentiation is inferred rather than stated.

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?

"Use it to judge whether a keyword is worth targeting" gives a decision context but no exclusions and no guidance on when to prefer keyword_metrics_sap, keyword_metrics_volatility, or keyword_top_apps instead. With this many keyword_* siblings, an agent still has to guess which call is cheapest for its need.

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