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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, non-destructive, openWorld), so the bar is lower. The description adds genuinely new behavioral context: it discloses the return shape (overall score plus itemized checks) and an operational constraint (free tier with limited daily use per IP). That rate-limit disclosure is exactly the kind of detail annotations cannot express.

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 verb and return value, then the improvement use case, then the operational caveat. Nothing is wasted, though the trailing 'etc.' is slightly loose and the return-value sentence could be tighter.

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 usefully explains what comes back (score + itemized breakdown). Rate limits and no-API-key operation are covered, and the required inputs are handled by the schema. Missing only guidance on failure modes or how the breakdown is structured, which is minor.

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 store, country, and store_id in detail (including enum values and storeId cross-reference to sonar_app_search). The description adds no parameter-level meaning beyond 'for an app', 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: 'Calculate an ASO (App Store Optimization) audit score (0-100) for an app.' The purpose is unambiguous and none of the sibling tools (keyword, screenshot, rankings, revenue) do the same thing, so an agent can route to it without confusion.

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?

It implies usage ('so you can identify what to improve') and notes it works without an API key, but never states when to prefer this over adjacent tools like sonar_app_overview, sonar_app_extract_keywords, or sonar_analyze_competitors, nor any prerequisites. Usage context is implied rather than prescribed.

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