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

Annotations already declare read-only, non-destructive, open-world behavior, and the description reinforces 'Read-only'. Beyond that it adds real behavioral context: the 1-credit cost and the variable return shape ('Ad text when Google returns it; otherwise format, dates and a preview link'), which the annotations do not cover.

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?

Compact and front-loaded: scope, source, return behavior, cost, and safety in a handful of clauses. Slightly telegraphic phrasing costs a bit of readability but nothing is wasted.

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 sketches the return shape (ad text or fallback fields plus preview link) and discloses the credit cost. Missing only guidance on the brand-cap implication of the brand parameter and when to prefer the Meta sibling.

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 baseline is 3. The description restates the domain/brand/country inputs but adds no syntax, default, or format detail beyond what the schema already documents.

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+resource: ads from Google Ads Transparency for a domain/brand in one country. The platform is named ('Google Ads Transparency'), which implicitly separates it from the sibling competitor_ads_meta, though the differentiation is not spelled out.

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?

No explicit when/when-not or prerequisite guidance. Usage is only implied by the source named ('Google Ads Transparency') versus the sibling competitor_ads_meta, which an agent must infer covers a different ad network.

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