Countries available for ranking

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

Annotations already establish read-only, idempotent, closed-world, non-destructive behavior, so the bar is lower. The description still adds real value: the city list is bundled (finite local dataset) and low result counts are expected rather than a failure, which prevents an agent from mistaking sparse output for an error.

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?

Two sentences, purpose front-loaded, followed by a useful caveat about expected result counts. The bracketed group/endpoint/cost metadata is structural noise rather than description content, but it is short and clearly segregated.

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 an output schema present, return-shape explanation is not required, and no parameters exist to document. The description covers what the data is (bundled list), what it contains (per-country counts), and the main interpretive pitfall. Only a note on whether the list is static versus refreshable 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?

The tool takes zero parameters, so the baseline is 4. The description adds no parameter claims that would conflict with the empty schema, and none are needed.

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?

"Which countries the bundled city list can rank, and how many qualifying cities each has" states a specific resource (countries) and the exact content returned (counts of rankable cities). It is clearly distinguishable from siblings like astroway_geo_acg or astroway_geo_acg_zones, though it never explicitly contrasts itself with them.

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 line about a country with two cities returning two results implies this tool is a discovery/sanity-check step before running rankings, but no explicit when-to-use or when-not-to-use statement is given. An agent must infer that this should be called before geo_acg to know which countries are supported.

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