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

With no annotations provided, the description carries the full behavioral burden. It discloses meaningful operational traits: cost is 1 credit, empty results and failures are free, caching can yield a free hit within 24 hours, and results are ranked. This goes well beyond a generic tool description, though it omits potential rate limits, error formats, or return structure.

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?

The description is short and generally front-loaded, but it repeats credit information: '1 credit when found; empty is free' is followed by 'Costs 1 credit. Empty results and failures are never charged.' This redundancy reduces conciseness. The overall structure is readable, but the duplication wastes a sentence.

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?

For a tool with no output schema and no annotations, the description covers cost, cache, and ranking but not the shape of returned results or when to choose this tool over similar siblings. The schema covers parameters well, but the description alone is not fully complete for an agent deciding whether and how to invoke it.

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 reinforces ranking and cache behavior, but those details are already covered by the q and cache parameter descriptions in the schema. The description adds little new meaning beyond what the input schema already provides.

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 states a clear verb and resource: 'Find Google Ads Transparency AR… entities — ranked multi-result.' It communicates that this is a search tool returning multiple ranked results. However, it does not explicitly differentiate from sibling tools like google_ad_library_ad_details or google_ad_library_company_ads, so the purpose is clear but the distinction from siblings is left implicit.

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?

The description provides no guidance on when to use this tool versus alternatives. It mentions caching and credit behavior, but does not explain when an agent should prefer advertiser_search over company_ads or ad_details, nor any exclusions or context that would route the agent correctly.

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