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

Annotations already declare readOnlyHint, openWorldHint, and destructiveHint=false, so safety is covered. The description adds genuinely useful context the annotations cannot: a first-lookup latency of up to a minute, a per-keyword price of $0.02, and the hard 25-keyword cap. It stops short of describing auth requirements or the returned value shape.

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 tightly packed sentences with no redundancy; the scope, latency, and price are all front-loaded. 'of your choosing' is the only mildly disposable phrase.

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 two-parameter, read-only lookup with no output schema, the description covers metric semantics, store choice, keyword limit, locale, latency, and cost. The only missing piece is any hint of the response structure (e.g., per-keyword numeric volume), which is a minor gap at this complexity level.

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 50%: 'store' is fully documented with enum values and default, while 'keywords' carries only maxItems/minItems. The description confirms the 25-keyword ceiling and adds a geographic/language qualification, but supplies no guidance on keyword form (phrases vs single terms), so it only partially compensates.

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 names a specific metric (monthly search volume), the resource it measures (App Store or Google Play keywords), and scope limits (up to 25 keywords, United States, English). However, it never contrasts itself with the sibling 'keyword_volume' tool, so the agent must infer that this one is the app-store-specific variant.

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?

There is no explicit when-to-use statement, no exclusion, and no named alternative. The presence of a sibling 'keyword_volume' makes the omission material: an agent cannot tell from the description alone which of the two applies to a given request.

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