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

Annotations already cover the safety profile (readOnlyHint, openWorldHint), so the description's job is to add context — and it does: it discloses the 2-credit cost and the shape of the result (matching apps with package ids). A credit cost is meaningful operational information not available elsewhere.

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 short sentences, zero waste, with the core action front-loaded and the cost disclosure placed at the end where a caller will still see it.

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 correctly covers the return shape (matching apps with package ids) and the cost. It doesn't mention pagination or result ordering, a minor gap for a search tool with a limit parameter.

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% — q, limit, store, and country are all documented with examples and enums. The description adds only mild emphasis that q accepts a phrase, so the schema is doing the heavy lifting.

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 a store for apps matching a name or phrase") and explicitly declares its role as the way to resolve a name into a package id for other tools, which separates it from the metrics/keyword siblings.

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?

Gives clear context for when to reach for it: resolving a name into a package id that the other tools consume. It does not name explicit exclusions or say when a sibling like keyword_app_suggestions is preferable, so it stops short of a 5.

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