list_countries

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It mentions filtering and localized names but does not describe pagination behavior (though schema includes limit/offset), ordering, return format, rate limits, or auth requirements. The description leaves significant gaps about how the tool operates beyond the schema fields.

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 exceptionally concise: two sentences with no unnecessary words. The core verb and resource are front-loaded, and every sentence adds meaningful information. Zero waste.

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 that there is no output schema and no annotations, the description should compensate by explaining return behavior, default sorting, or pagination details. It only covers filtering and localization, ignoring the limit/offset parameters and overall response structure. For a listing tool with 5 optional parameters, this is insufficient for an agent to predict behavior reliably.

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, providing clear meanings for all five parameters. The description adds marginal value by summarizing 'name prefix', 'telephone code', and 'preferredLanguages for localized names', which aligns with the schema descriptions. It does not elaborate on parameter formats or interactions beyond what the schema already states.

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 uses the specific verb 'List' and identifies the resource as 'countries' with filtering options. It clearly distinguishes from sibling tools like 'get_country' (single country) and 'search_cities' (different resource). The mention of optional filtering by name prefix or telephone code adds precise 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?

The description indicates optional filtering and localized name support, giving context for when to use. However, it does not explicitly state when not to use this tool versus alternatives like 'get_country' for detailed info or 'country_overview' for an overview. No exclusions or conditions are provided.

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