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

The description adds substantial behavioral context beyond the annotations: results are ordered 'newest first', an unfiltered query 'will be truncated', and data only exists for 'apps the user tracks'. These are important operational characteristics that help set expectations and guide filtering, going beyond the read-only and idempotent hints already provided.

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?

The description is three purposeful sentences plus an example, with the core functionality stated first. Every sentence adds value: purpose, filtering caveat, scope limitation, and a concrete usage example. No redundant fluff.

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?

Given the tool has 7 parameters and an output schema, the description provides a good high-level context: it states the use case, ordering, truncation risk, data availability scope, and a real-world example. However, it could be more complete by explicitly linking parameters to their roles and describing pagination behavior, though the output schema may cover return structure.

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?

With schema description coverage at 0%, the description must compensate for parameter understanding. It mentions filter dimensions (country, platform, chart type, category) and the example implies time range ('over the last month') and app identification ('my app'), but it does not explicitly explain 'limit', 'sinceDays', or 'appStoreId' semantics. The truncation warning indirectly hints at 'limit', but overall parameter meanings are only partially conveyed.

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?

The description clearly states the tool returns 'raw rank observations, newest first' for trend questions, which is a specific verb+resource with an explicit purpose. It distinguishes from siblings by noting it applies to 'apps the user tracks' and focuses on historical data for trend analysis, unlike current-rank or chart-list tools.

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 provides clear guidance on when to use it ('for trend questions') and includes a concrete example question. It warns about the need to filter by country/platform/chart type/category to avoid truncation, and mentions the prerequisite that only tracked apps have history. However, it does not explicitly name alternative tools for when this one should not be used.

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