list_country_codes

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

With no annotations, the description carries the behavioral disclosure burden. It reveals that this is a GET operation, that it returns country codes, and that station counts are included. It does not specify behavior for countries with zero stations, but for a simple listing endpoint the key behavior is adequately disclosed.

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?

A single sentence that front-loads the resource and result contents, then appends the endpoint. Every word earns its place; there is 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?

The tool is simple with one optional generic parameter and an output schema, so the description covers the essential call context. The main gap is the lack of guidance distinguishing this from closely related country/list endpoints, but the definition remains sufficient for correct invocation.

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 description coverage is 0%, and the only parameter, timeout, is not mentioned in the description. The description adds no meaning beyond the schema's name/default, leaving the timeout's behavior and units to inference.

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 names a specific verb ('list'), a clear resource ('ISO 3166-1 country codes'), and a distinguishing feature ('with station counts'). It also gives the exact endpoint, making the tool's purpose unambiguous and differentiating it from siblings like list_countries or find_stations_by_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 this when you need ISO 3166-1 country codes with station counts. However, it does not explicitly state when to prefer this over related tools such as list_countries or find_stations_by_country_code, nor does it provide any exclusions.

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