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

Annotations already establish readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so safety is covered; the description goes further by disclosing non-obvious behavior: brand_name is matched literally, country/city-qualified strings return nothing, and results span all countries so the agent must pick by region. It does not discuss rate limits or result volume, but the failure-mode disclosure is genuinely useful beyond the annotations.

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?

A single dense block that is well front-loaded: usage trigger first, then what it returns, then parameter pitfalls, then result interpretation. Every clause earns its place, though the matching rules and result-scoping advice are packed tightly enough that a slight restructuring would improve scannability.

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?

Output schema exists, so return-value detail is correctly omitted, and annotations cover the safety profile. The description completes the picture with trigger conditions, parameter pitfalls, and next-step routing; the only untouched area is what to do when multiple advertisers match beyond the brief 'pick the one whose region matches'.

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%, including the 'bare brand name or bare domain, not both, and no country or city' rule, so the schema already carries the semantics. The description largely restates that constraint and adds only the consequence ('returns nothing'), which is a marginal gain over the structured fields.

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 (looks up) and resource (advertiser ID and domain) in a named system (Google Ads Transparency Center), and positions itself relative to siblings by calling itself the 'first step before get_google_ads'. An agent can distinguish it from get_google_ads, get_google_ad_details, and get_meta_platform_id without opening any 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?

Explicitly scopes usage to researching a brand's Google advertising on Search, Display, or YouTube, names the follow-up tool (get_google_ads), and gives a when-not rule via the input constraint (never pass country/city qualifiers). Nothing about selection 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.