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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is fully covered structurally. The description's only added behavioral information is 'when available' for the star histogram, signaling partial/optional fields — useful but thin. Nothing about behavior for unknown ids, store mismatch, or country fallback.

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?

One front-loaded sentence with no filler; the caveat '(when available)' is placed inline rather than wasting a separate sentence. It is telegraphic rather than ungrammatical, and nothing could be trimmed without losing field information.

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 necessary work of naming the returned fields, which is appropriate for a read-only lookup. However, it omits failure behavior (app not found), whether the histogram is separate data or an aggregate, and any guidance on selecting between this and the other per-app tools — gaps for a tool with three siblings operating on the same app.

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%, and the schema already explains accepted appId forms, store inference, and the country default. The description adds no parameter guidance beyond the schema, 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?

The description enumerates the exact payload (name, developer, category, price, rating, rating count, star histogram) for a single app, which makes the resource and its boundaries clear against siblings like get_app_reviews or get_version_history. It never states the retrieval verb or that it is a single-app lookup, relying on the tool name for that, so it falls just short of a 5.

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 statement of when to call this versus get_app_reviews, get_pain_trend, get_version_history or search_apps, and no prerequisites are given. The only routing hint ('get ids from search_apps') lives in the appId schema description, not in the tool description.

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