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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior, so the description does not need to restate safety. It adds valuable context by specifying exactly what the call returns, including the star-level breakdown and an example invocation, which helps the agent anticipate the response shape despite the absence of an output schema.

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 compact and front-loaded: it opens with the core result fields, then provides a realistic invocation example and clarifies the app_id domain. Every sentence earns its place 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?

For a simple three-parameter read-only tool with full schema coverage and no output schema, the description is complete: it explains return values, shows an example call, and clarifies supported id formats. There are no critical gaps that would prevent correct invocation.

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 parameters are already fully documented. The description adds a concrete usage example and re-emphasizes the app_id format, which is mildly helpful but does not meaningfully extend what the schema already provides.

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 that the tool returns a ratings summary for an app: average rating, total count, and star breakdown. It distinguishes itself from siblings like appfollow_reviews and appfollow_aso_keywords by specifying the ratings-focused resource, though it uses a noun phrase rather than an explicit verb like 'get'.

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 described output fields imply the tool should be used when an agent needs rating aggregates rather than individual reviews or keyword data, but it never explicitly says when to choose this tool over siblings or when not to use it. There are no alternative tool mentions or exclusions, leaving usage to inference.

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