List Country Codes

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

With no annotations provided, the description carries the behavioral disclosure burden. 'List' makes the read-only nature clear, and naming the ISO standard and CEF EN 16931 source adds useful context about the data. No hidden side effects or surprising behavior are evident for this zero-parameter listing operation.

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 a single concise sentence with no filler. Every word contributes: the action, the code standard, and the source list are all present and front-loaded.

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 zero-parameter list tool with an output schema available, the description is largely complete: it states exactly what will be listed and from which source. A small gap is the lack of explicit guidance on when to choose this over check_country_code, but this is a minor omission for such a simple operation.

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 zero parameters and schema description coverage is 100%, so there is no parameter meaning to add. The baseline for a no-parameter tool is 4, and the description appropriately focuses on what is returned rather than inputs.

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 a specific verb ('List') with an exact resource ('ISO 3166-1 alpha-2 country codes') and a clear source ('CEF EN 16931 code list'). This clearly distinguishes the tool from siblings like check_country_code, which validate individual codes rather than listing them.

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 intended use is implied by the verb and resource: use this when a list of country codes is needed. However, the description does not explicitly contrast it with alternatives such as check_country_code or discuss when not to use it, so some guidance is left to inference.

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