list_countries

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

No annotations are provided, so the description carries the burden. It does disclose the payment cost ($0.001 USDC via x402) and categorizes the tool, which adds useful context. However, it omits return shape, optional parameters, pagination, or any side effects, limiting transparency.

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 short and front-loaded, with no filler words. The cost and category are useful, though the brevity borders on under-specification rather than disciplined conciseness.

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 relatively simple, and the name conveys the primary function, but the lack of an output schema and the opaque generic parameter object leave significant gaps about the return data and invocation parameters. The cost disclosure helps but is not enough for confident use.

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 only parameter is a generic 'params' object with the unhelpful description 'Tool parameters as JSON object'. The tool description adds no parameter details, so an agent cannot know what filters, fields, or options are acceptable.

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 action ('list') and the resource ('countries'), which distinguishes it from sibling list_* tools like list_currencies and list_languages. However, it provides no details about the output format or what country attributes are returned.

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?

No guidance is given on when to use this tool versus alternatives. The 'Data & Weather tool' category is too broad and does not help an agent choose among the many sibling tools, nor does it mention exclusions or alternative tools.

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