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 discloses that the tool returns a JSON string with a list of countries, which is useful. However, it doesn't mention pagination behavior beyond parameter names, potential rate limits, or whether the list is exhaustive or filtered by default. The description is adequate but not rich.

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 concise and well-structured: a one-line summary, a context sentence, and a clear Args/Returns breakdown. Every sentence earns its place. It could be slightly more compact, but it's appropriately sized for a simple list tool.

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, has no required parameters, and has an output schema, so the description doesn't need to explain return values in detail. It covers the purpose, parameters, and return type. However, it lacks guidance on when to use this vs. sibling list tools and doesn't mention any edge cases like empty results or pagination limits beyond the max page_size.

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%, so the description must compensate. It does explain each parameter: name filters by partial match, page starts at 1, page_size max 1000. This adds meaning beyond the schema, which only provides types and defaults. However, it doesn't clarify the default page_size behavior or the exact format of the name filter (e.g., case sensitivity), so it's not fully compensating.

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 states a clear verb and resource: 'List all countries.' It also adds context that countries are used when specifying location addresses, which helps distinguish it from other list tools. However, it doesn't explicitly differentiate from sibling tools like list_regions or list_locations, so it loses a point.

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 context by saying countries are used when specifying location addresses, which gives a hint about when to use it. However, it doesn't explicitly state when to use this tool versus alternatives like list_regions or list_locations, nor does it mention any exclusions or alternatives.

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