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

Annotations already cover safety (readOnlyHint, idempotentHint, destructiveHint) and open-world access, and the description goes well beyond them: free tier without an API key, per-IP daily limits, a throttling fallback that returns stored data shaped as { data, meta } with meta.stale/stale_as_of, and a directive to pass meta.note to the user. This is exactly the operational context structured fields cannot convey.

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?

Long for a search tool but front-loaded with purpose first, then the ranking caveat, then alternatives, then operational notes. Every sentence carries distinct, decision-relevant information with no filler or repetition.

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?

Despite having no output schema, the description explains what comes back, how to interpret iOS ordering, and the degraded throttled response shape. Combined with ratings independent of rank order, an agent has everything needed to call and correctly report 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%, so all four parameters (query, store, num, country) are already fully documented, including enum, defaults, and range. The description adds the return metadata fields (name, developer, icon, rating) but no additional parameter meaning, so the baseline 3 is correct.

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 (search/find) and resource (apps in App Store / Google Play) and names the concrete use case of obtaining a store ID before calling other tools. It explicitly distinguishes itself from the ranking tools, so an agent can tell it apart from sonar_app_rankings and sonar_top_charts without opening any 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?

Gives an explicit when-to-use (get an app's store ID), an explicit when-NOT-to-use (never treat list position as rank), and names the alternatives to use instead (sonar_track_keywords, sonar_app_rankings, sonar_keyword_rankings). This is about as complete a routing instruction as a search tool can carry.

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