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

Annotations already declare read-only, idempotent, open-world, and non-destructive behavior. The description adds useful context that the call returns rank and score in one request and that direction defaults to 'most_peaceful', but it does not discuss coverage limits or edge cases.

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?

Front-loads the core ranking capability, then adds a compact list of preferred query phrasings and the default direction. No sentence is wasted, and the examples directly support invocation.

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?

With only two optional parameters, full schema coverage, and rich annotations, the description supplies everything needed: what the ranking returns, how direction works, and which natural-language queries select this tool. No output schema is needed for this simple ranked list.

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 100%, so the schema already documents both limit and direction, including defaults and enum values. The description adds only marginal emphasis on direction defaulting to 'most_peaceful', which is also in the schema, so baseline 3 is appropriate.

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?

States a specific verb and resource: ranks countries by Global Peace Index score, returning either the most or least peaceful countries with rank and score. The ranking scope is clear, but it does not explicitly distinguish itself from the sibling gpi_country_score tool, so it falls short of the top score.

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?

Gives explicit usage contexts via 'PREFER for' example phrases such as 'most peaceful countries' and 'top 10 most peaceful nations'. It does not state when not to use this tool or name an alternative such as gpi_country_score, so it is clear but incomplete.

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