App details

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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the description's job is to add context beyond that, which it does: store-dependent field availability, approximate/rounded installs, currency in Toman with 0 = free, and no binary download. It stops short of error behavior (e.g., unknown package) or rate limits.

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?

Front-loaded with the core purpose and return fields, then progressively adds store-specific and unit caveats; every sentence carries information. The middle sentence is dense and list-like, which slows scanning slightly, but nothing is filler.

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 must carry the return-value burden, and it does so well: field list, store-specific extras, precision caveats, and currency semantics. Remaining gaps are minor (failure modes, whether fields can be null for a given store).

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%, so the baseline is 3, but the description earns extra credit by explaining the consequence of the store enum value (Bazaar adds version_code, histogram, changelog, permission count; Myket adds first publish date and developer_id). The package parameter's meaning is only implied by 'one app's metadata'.

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 gives a specific verb+resource ('Get one app's metadata from one store') and immediately enumerates the returned fields, so the agent knows exactly what the tool produces. It also explicitly distinguishes itself from ap_compare and from APK-download tools, making sibling selection 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?

It routes the agent to an alternative with a condition ('To see both stores at once use ap_compare') and states a scope exclusion ('Metadata only: no APK download'). It does not, however, contrast with ap_search or ap_similar, which occupy adjacent lookup use cases.

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