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

Annotations already declare readOnlyHint=true and idempotentHint=true. The description adds meaningful detail: it specifies 'Appskyline has synced' (indicating cached data) and 'never downloads from or uploads to the store,' reinforcing and extending the annotation. It also highlights the keyword character-count check against Apple's 100-character limit, providing extra behavioral context beyond the 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 two concise sentences, front-loaded with the core purpose and followed by relevant details. Every phrase earns its place: the field list is specific but not redundant, and the read-only assurance is placed at the end without padding. No fluff or 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?

For a read-only tool with an output schema and full parameter descriptions, the description sufficiently covers what data is returned and the safe behavior. It mentions the synced nature and the character-limit detail. It doesn't discuss error conditions or rate limits, but given the tool's simplicity and the presence of an output schema, this is not a significant gap. Could add a note about default locale behavior but is already complete enough.

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?

The input schema provides descriptions for all three parameters (appId, store, locale) with 100% coverage. The description's mention of 'per locale' complements the locale parameter, and the listing of fields hints at the store parameter's role, but it doesn't add deeper meaning about parameter values or constraints. Since schema already documents the parameters, a baseline 3 is appropriate.

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 opens with 'Read the store-listing metadata' — a clear verb and resource — and enumerates the exact fields returned (per locale name, subtitle, keywords with character counts, promotional text, release notes, version, review state). It also states 'Read-only: it never downloads from or uploads to the store,' which distinguishes it from sibling tools like get_store_listing, making its purpose 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?

The description provides clear context: it reads synced metadata from Appskyline, implying its use when cached listing data is needed. It explicitly states it is read-only and never contacts the store, which signals a safe, non-mutating operation. However, it doesn't name alternative tools or explicitly state when NOT to use it, so it lacks the full when/when-not guidance that would earn a 5.

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