search_ad_library

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

With no annotations provided, the description must carry the full burden of behavioral disclosure. It only says 'Search' and 'Useful for competitive research and transparency,' which implies read-only, but it does not explicitly affirm read-only behavior, mention authentication/authorization requirements, rate limits, pagination, or what data is returned. This leaves significant behavioral ambiguity.

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?

Three short sentences, front-loaded with the core purpose, followed by supporting detail and use case. No redundancy or filler—every sentence 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?

Given no output schema, the description should explain what the response contains (e.g., ad fields, creative, impressions), but it is silent on return value structure. It also lacks mention of pagination behavior, result count defaults, or error scenarios. The tool has 7 parameters and no output schema, so this is a meaningful gap.

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?

The input schema has 100% description coverage, with all seven parameters individually described. The description adds no new semantics beyond restating that searching is possible by keywords, countries, and ad type, which maps to search_terms, ad_reached_countries, and ad_type but adds no syntax, format, or usage nuance. Baseline 3 is appropriate.

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 starts with a specific verb+resource: 'Search the Meta Ad Library for ads.' It clearly states the function and distinguishes it from sibling tools like list_ads or get_campaign_ads, which deal with the user's own ad objects. The added detail (keywords, countries, ad type) further clarifies 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?

'Useful for competitive research and transparency' provides some context, implying a public-search use case, but it does not explicitly state when to prefer this tool over alternatives or mention exclusions (e.g., not for retrieving your own campaign ads). There is no direct comparison with sibling tools.

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