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

Annotations already declare readOnlyHint and destructiveHint, so the description adds value by disclosing the cost (1 credit vs 25) and that the detailed variant is deliberately not exposed. It also specifies the exact JSON return shape, which is not in the schema. While it doesn't cover pagination, the safety profile is already carried by annotations, and the description provides meaningful behavioral context beyond them.

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 sentences with no filler. The first sentence front-loads the purpose and usage, the second discloses cost and return format. Every clause earns its place.

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?

Covers purpose, alternative, cost, and return format; annotations cover safety. It lacks explicit mention of pagination or handling multiple results, but the limit parameter schema addresses this and the tool is simple enough that the description is nearly complete.

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 the baseline is 3. The description repeats that search can be by domain or advertiserId, but does not add new meaning beyond the schema's parameter descriptions. It mentions the return fields but not parameter-specific nuances, so it does not exceed the baseline.

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 clearly states a specific verb ('pull') and resource ('Google Ads Transparency') for exactly one advertiser by domain or advertiserId. It distinguishes itself from the sibling research_ads by naming the alternative explicitly, leaving no ambiguity about scope.

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 says 'use when you know the brand; use research_ads for open-ended research,' providing a direct condition and naming the alternative. Also explains the cost trade-off between the cheap BASIC listing and the expensive detailed variant, giving concrete guidance on when this tool is appropriate.

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