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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. Beyond that the description adds real behavioral facts the annotations do not carry: results are public, one result per product is shared for 24 hours, and the full check is limited to once per account. Missing only failure behavior for malformed links or rate limits on the free path itself.

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 core capability and its input types are front-loaded in the first clause, with exclusions and quota caveats following. It is a dense single paragraph and the parenthetical asides make the second half slightly hard to parse, but every sentence carries information an agent would otherwise have to guess.

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 one required parameter and no output schema, the description carries the return-value burden itself and does so qualitatively — naming the listing facts and the SEO/link findings. It is adequate for a simple read tool, though it does not say what happens on an unresolvable or unsupported input.

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 coverage is 100% for the single `link` parameter, so the baseline would be 3. The description earns more by explaining that the same field accepts two semantically different input kinds — an App Store link/id versus a website domain/URL — and that the kind of input determines which class of result is returned.

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 names a specific verb and resource pair — a free public read of either an App Store app (link or id) or a website (domain) — and states exactly which facts come back (US listing name/genre/rating, or what the home page shows search engines). It also delimits scope by excluding Google Play and by contrasting itself with the fuller paid check, so an agent can separate it from the sibling tools without reading their schemas.

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 clear when-to-use context (a quick, free, single-product lookup) and an explicit when-not (Google Play is not supported). It also explains the relationship to the full check, which requires the owner to sign up and run it from the returned page, giving the agent a routing signal. It stops short of naming the sibling tool to call (e.g. start_sign_up) for that escalation, which keeps it from a 5.

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