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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds behavioral context by specifying that each city includes geographic coordinates, IANA timezone, DST-aware UTC offset, and that cities are sorted by population descending. It does not mention pagination or rate limits, but these are not critical given the 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?

The description is three sentences, front-loaded with the core action, followed by data field details and ordering. Every sentence provides value—what it returns, what data is included, and how results are sorted—without any fluff.

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 read-only tool with 4 parameters and no output schema, the description covers purpose, data fields, ordering, and use case. Pagination is handled by schema parameters, so the description does not need to explain it. It could arguably mention that results are paginated, but the schema makes that inferable.

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%, and the schema already documents all parameters (iso2, limit, offset, compact) with examples and constraints. The description repeats the country code examples but adds no new parameter-level semantics beyond what the schema provides, so it stays at the baseline.

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?

Description uses specific verb 'Returns' with resource 'all cities for a specific country', clearly identifying the tool's action. It distinguishes from sibling tools by focusing on country-code-based lookup and population-sorted output, as seen in the title and description.

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 clearly indicates this tool is for retrieving cities by ISO country code, with examples and use cases (astrology calculations). However, it does not explicitly contrast with sibling tools like get_location_search or state when NOT to use it, so exclusions are implicit rather than explicit.

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