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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety is covered by structure. The description adds genuinely non-structured behavior: the per-record credit cost with a minimum of 2, which directly affects how the agent should size requests. It stops short of describing pagination limits or return shape, but the cost disclosure is a real contribution beyond annotations.

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?

Three sentences, zero filler, front-loaded with the core verb+resource before the cost caveat and the sibling routing. Every sentence 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?

With an output schema present, annotations covering safety, and 100% schema description coverage, the description only needs to add scope, cost, and routing — which it does. Nothing an agent needs to call this correctly is missing.

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 the schema carries the semantics of all 12 parameters and a baseline of 3 applies. The description adds meaning the schema lacks by tying page_size to the credit cost, turning a plain integer into an economic tradeoff the agent must reason about.

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?

States a specific verb and resource ('Search the pre-resolved mobile-app index') and enumerates the filter dimensions (store, platform, developer, price, rating, category). It explicitly distinguishes itself from the two app-domain siblings by naming them, so an agent can route without opening any schema.

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?

Names both alternatives explicitly (datasets_apps_reviews_search for review data, datasets_apps_charts_search for chart data) and states what each covers, giving clear routing. It also gives a cost-driven usage rule ('keep page_size to what you need'). Nothing critical 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.