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

Annotations already cover readOnly, idempotent, non-destructive and non-open-world, so the safety profile is established. The description adds context annotations cannot carry: it is free and requires no account, and results are returned most-populous-first with an id per area, which is behavioral/return detail absent from structured fields.

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?

Four tight sentences with no filler. The most decision-relevant fact (free, no account needed) is front-loaded, followed by the call patterns and the disambiguation rule.

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?

There is no output schema, but the description compensates by describing the return shape (areas ordered by population, each with an id) and the downstream use of that id. Together with annotations and the fully documented schema, nothing needed to call this correctly is missing.

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%, which sets a baseline of 3. The description goes beyond the schema by explaining the interaction of parameters: no q means browse, no country means the country list, and the returned id is the value to hand to search_areas for ambiguous names.

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 specific verb and resource ("Look up the areas search_areas accepts in a country") and explicitly ties itself to the sibling tool search_areas, so an agent can distinguish the discovery step from the search step. It also defines scope (per-country) and output ordering up front.

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?

It gives explicit call patterns: omit q to browse, omit country to list countries, and pass a specific id when a place name is ambiguous (four Houstons, thirteen Springfields). That is concrete when-to-do-what guidance. It does not mention sibling alternatives such as estimate_area_search for sizing an area, so it stops short of full routing.

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