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

With no annotations, the description carries the full burden, and it does disclose useful behavioral facts: the identifier can be an id, package name, or store URL, and it lists the fields returned. However, it says nothing about failure behavior for invalid apps, permission/auth requirements, or rate limits, so the safety and error profile remains opaque.

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 compact sentences with zero filler; the resource, sources, and acceptable identifier formats are front-loaded before the use-case hint. Every clause earns its place.

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?

An output schema exists, so enumerating return values is a bonus rather than a requirement, and the description covers inputs and scope adequately. The only real gap is the unexplained 'country' parameter, which an agent must infer from the schema alone.

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 0%, so the description must carry the parameter semantics. It does a good job for the required 'app' parameter by enumerating three accepted identifier forms, but the 'country' parameter (and its 'us' default) is never mentioned anywhere, leaving half the inputs undocumented.

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?

Names the resource (mobile app details), the supported sources (App Store / Google Play), and enumerates the returned fields (developer, rating, installs, price, etc.), which is much more specific than the title. It distinguishes itself from app_store_search and app_store_reviews only implicitly through the word 'details', but the field list makes the scope unambiguous.

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?

'Use for app or competitor research' gives a general context but no explicit when-to-use/when-not-to-use guidance. It never says to use app_store_search to first find an app or app_store_reviews to get reviews, so the routing among the three app_store siblings is left to inference.

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