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

Annotations already cover the safety profile (readOnly, openWorld, non-destructive), and the description adds genuine context beyond them: per-call and per-keyword pricing, the 1,000-keyword ceiling, and the important clarification that 'competition' is ad competition (0-1), not ranking difficulty. It stops short of describing pagination, latency, or failure behavior for oversized requests.

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 tight sentences lead with what is returned and what it costs; every clause carries information (limits, metrics, pricing) with no 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 usefully enumerates the return fields (volume, CPC, competition, 12 months of history), which is exactly the burden it must carry. Cost and scoping limits are present; only error/edge behavior is unaddressed.

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 67%, and the schema already documents the country/language defaults and the maxItems=1000 cap. The description reinforces the single-country/single-language-per-call constraint and the 1,000 limit but adds no format or syntax detail beyond the schema, so 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 names the specific resource (Google search volume) plus the exact metrics returned (CPC, ad competition, 12-month history), which is far more than a restatement of the name. It implicitly contrasts with the app-store sibling via 'Google', but never names an alternative explicitly.

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?

Usage is only implied by the cost and the 'up to 1,000 keywords in one country and language' scoping; there is no statement of when to choose this over app_keyword_volume or how to batch multi-country needs. The pricing line indirectly shapes the decision but isn't framed as guidance.

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