list_country_codes

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

No annotations are provided, so the description carries the burden of behavioral disclosure. It clearly indicates a read-only enumeration and specifies the source list (CEF EN 16931), which is sufficient for this simple no-parameter tool. It does not overstate side effects or hide mutation behavior.

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 one concise sentence that front-loads the action and the exact resource. Every word adds specification, with no filler or repetition.

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, the description is complete: it names the exact code standard (ISO 3166-1 alpha-2) and the source list (CEF EN 16931). No prerequisites, permissions, or side effects need disclosure for this straightforward read-only 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 tool has zero parameters and the schema description coverage is 100%, so baseline 4 applies. The description adds no parameter semantics because there are no parameters requiring documentation.

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') and resource ('ISO 3166-1 alpha-2 country codes from the CEF EN 16931 code list'), making it clear what the tool returns. This distinguishes it from sibling tools like list_currency_codes, list_payment_means_codes, and check_country_code.

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 implies usage: call it when you need the list of allowed country codes. However, it does not explicitly say when to prefer it over the sibling check_country_code or other list_* tools, nor does it describe exclusions or alternatives.

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