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

No annotations are provided, so the description carries the full burden and does so: it discloses the billing cost ('Costs 1 credit'), the silent country fallback, the no-paging/no-offset constraint, and crucially the cap semantics ('A response holding exactly that many rows is capped, not complete'). This is the kind of non-obvious behavior an agent could not infer from the schema alone.

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?

Front-loaded with the core purpose and return shape, then progressively layers usage, exclusions, cost, and the cap caveat. The length is justified because every sentence adds a distinct operational fact; there is no filler or restatement of the name.

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?

There is no output schema, so the description must describe the return payload and it does (titles, descriptions, URLs, domains, SERP feature flags). Combined with cost, cap behavior, and operator limitations, an agent has everything needed to call this correctly and interpret the result.

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 100%, so defaults, ranges, and codes are already documented and the baseline is 3. The description adds genuine meaning on top: it explains that 'results' is a hard cap rather than a target, and instructs 'raise the row count in a SINGLE call, up to its maximum, rather than calling again', which the schema does not convey. The keyword constraint is duplicated from the schema, keeping it below a 5.

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 ('See who you're actually up against for a keyword. Returns the results on page one right now') and enumerates exactly what comes back: titles, descriptions, URLs, domains, and SERP features. It explicitly contrasts itself with Search Console ('it can never tell you who holds position 1'), so an agent can separate it from the ranking/reporting siblings without opening a 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?

Gives concrete when-to-use triggers: 'before writing against a keyword', 'before rewriting a meta title for a Low-CTR insight', and 'to judge whether an AI overview is eating the clicks'. It also states a hard exclusion ('Search operators such as site: are not supported'), which prevents a common misuse. Nothing 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.