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

With no annotations, the description must carry the burden of behavioral disclosure. It states the tool searches and returns location keys but does not disclose return format, pagination, error behavior, or any side effects. The only added nuance is the country-code note, which is insufficient for a search tool that may have rate limits or data constraints.

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 country-code note is a valuable addition. It is compact and front-loaded with purpose. A slight deduction because adding a little more detail on parameters or output would not hurt.

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 4 parameters and no output schema or annotations, the description is minimal. It does not explain what a valid query looks like, what location_types values are allowed (though defaults are given), or what the return structure is. An agent would need to infer these from sibling patterns or trial-and-error, so completeness is low.

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 coverage is only 25% (country_code has a description), and the tool description does not clarify the remaining parameters (query, limit, location_types). The country-code note does not address parameter usage. The description adds no value to parameter understanding beyond the schema's single description.

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 the tool searches Meta city/region location keys for ad targeting, a specific verb-resource combination. It distinguishes from Google's geo-search sibling by specifying 'Meta', and the country-code note prevents misuse. This unambiguously defines the tool's function.

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 one implicit usage rule (do not use for country ISO codes) but does not explicitly state when to prefer this over other search tools like adsap_search_interests or adsap_google_search_geo_targets. The Meta qualifier hints at platform differentiation but no alternatives are named. Guidance is present but minimal.

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