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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows it is safe. The description adds meaningful behavioral context beyond this: results are sorted alphabetically, cover specific global regions, and include city counts. This adds value without contradicting annotations.

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?

Three sentences, no wasted words. The first sentence states the core output, the second gives concrete use cases, and the third adds sorting and regional scope. Information is front-loaded and structured.

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?

For a simple list tool with no output schema and 3 optional pagination/format parameters, the description is complete enough: it covers purpose, use cases, sorting, and coverage. It does not explain pagination behavior, but the schema provides that, and the tool's simplicity does not demand more.

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 all three parameters (limit, offset, compact) are fully documented in the schema. The description does not add additional parameter semantics, and with full schema coverage the baseline of 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?

The description clearly states the tool returns all countries with ISO alpha-2/alpha-3 codes and city coverage, using a specific verb ('Returns') and resource ('every country'). It implicitly distinguishes from the sibling get_location_countries_iso2, which likely returns only ISO2 codes, and from get_location_search by focusing on list-level metadata.

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 explicitly names use cases: building country dropdown menus, regional filters, and checking city coverage before querying. It does not explicitly mention when not to use it or name alternatives, but the use cases are clear and well-contextualized, making sibling differentiation implicit.

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