zcell_list_sim_usage_by_country

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

The description adds useful behavioral context beyond the readOnlyHint annotation: it specifies a 'days lookback window' and that it returns 'top countries'. This clarifies the impact of the `days` and `limit` parameters. No contradictions with annotations exist; the 'Read-only' statement aligns with readOnlyHint. It does not disclose details like sort order or exact return fields, but it is sufficiently transparent for a read-only list tool.

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 two sentences, front-loaded with the main action, and contains no redundant or filler content. Every sentence earns its place, making it efficient and easy to parse.

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 read-only list tool with no output schema, the description covers the core behavior: what is returned (top countries), the time window parameter, and the read-only nature. It could mention whether results are sorted by usage descending or what fields each record contains, but these are minor gaps. Overall, it is complete enough for an agent to understand and invoke the tool correctly.

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?

With only 33% schema description coverage, the description compensates by explaining that `days` controls the lookback window and that the result is 'top countries', implying `limit` controls how many countries are returned. The `query` parameter is already fully described in the schema. Thus the description adds semantic meaning to the otherwise under-described parameters.

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 starts with 'List Zscaler Cellular data usage grouped by country', which clearly states the verb (list), resource (Zscaler Cellular data usage), and grouping (by country). The parenthetical '(top countries)' further clarifies the output scope. This distinguishes it from sibling tools like zcell_list_sim_usage_by_sim and zcell_list_sim_usage_by_day, which group by different dimensions.

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 provides clear context: it returns the top countries by data usage over a days lookback window, implying when to use it (country-level aggregation). However, it does not explicitly contrast with alternatives such as by-SIM or by-day tools, nor does it state exclusions. The grouping information alone makes the intended use evident, but explicit when-not-to-use guidance is missing.

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