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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It adds a billing cost ('Billing per call: 1 Credits') and specifies the output (all country codes), but it doesn't explicitly state read-only semantics, authorization needs, or response format. The cost disclosure adds some transparency, but the overall behavioral picture is incomplete.

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 consists of two short sentences, front-loaded with the main purpose and immediately followed by cost information. Every sentence earns its place with no redundancy or filler.

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?

Given the tool's simplicity (0 parameters, no output schema, no annotations), the description provides the essential context: it returns all country codes and costs 1 credit. It doesn't mention usage guidance or output format, but the core invocation context is sufficient for a 0-param reference data tool.

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 additionalProperties set to false, so there are no parameter details to document. With zero parameters, the baseline is 4, and the description correctly avoids adding irrelevant parameter semantics. The schema already fully covers the parameter space.

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 a specific verb-resource pair: 'Get list of all country codes.' It specifies the full scope ('all') and is distinct from the sibling get_api_v1_search, which likely performs searches rather than returning a reference list.

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 provides no guidance on when to use this tool versus the sibling get_api_v1_search. It doesn't mention alternative use cases, exclusion criteria, or prerequisites, leaving the agent without context for tool selection.

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