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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description is not obligated to restate that. It instead adds substantive behavior: results are deterministic, the scanned set is bounded, and the agent must surface coverage.truncated and completeForWindow because counts are not population-wide. The only missing piece is how truncation is triggered.

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?

Two sentences, no padding: the aggregation scope comes first, the reporting obligation second. Every clause carries information the agent needs.

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?

For a 7-parameter, zero-required, no-output-schema tool, the description does the heavy lifting by naming two result keys the agent must report, and by framing results as a sample rather than a total. It leaves open what happens with an empty filter set and what the actual response envelope contains.

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?

The phrase 'by rating, collection day, locale and reported version' maps filters onto ratings, since/until, locale, and version, and 'reported' hints at the sparsity already noted in the schema. With schema coverage at 57%, the query parameter's interaction with counting (filter-then-count) and the zero-required-parameter default behavior are left unaddressed.

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 output ('compute deterministic counts') plus the exact dimensions aggregated ('by rating, collection day, locale and reported version'), which distinguishes it from a listing/search tool. It stops short of naming the sibling tools it is not, so the differentiation is inferred rather than declared.

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?

There is no explicit when-to-use or when-not-to-use statement and no named alternative among get_review, search_reviews, or list_apps. The purpose implies it is the aggregation path rather than the retrieval path, but the agent must infer that itself.

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