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

With no annotations, the description carries the behavioral burden. It discloses the free price (0¢), fuzzy token-based matching, synonym handling, ABS field-code coverage, and field count (~17k). It stops short of covering auth or rate-limit behavior, but the concrete query example and matching semantics provide solid expectation-setting.

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 front-loaded with the core purpose and remains information-dense throughout. The only minor redundancy is stating the free price twice: 'Free (0c)' at the start and '**Price: 0¢ per call.**' at the end.

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 two-parameter discovery endpoint with an output schema, the description is complete: it covers purpose, pricing, matching behavior, a worked example, available field volume, and the downstream route. The output schema handles return-value details, so nothing critical 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 coverage is 100%, so the baseline is 3. The description adds value beyond the schema by explaining exactly how fuzzy matching behaves, including plural handling and Census synonyms, and by showing the verbatim `query=couples with children` scenario. This enriches both `query` and `limit` semantics.

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 opens with a specific verb and resource: 'Discover which statistical fields exist.' It then gives a concrete example and clarifies that returned field codes feed into the values route, distinguishing it from the nearby area_stats_values and area_stats_regions siblings without ambiguity.

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 clearly establishes the intended workflow: first discover field codes here, then use them with the priced `/area-stats/SAL/{suburb}/values` route. It does not explicitly name sibling tools or state when not to use them, but the routing guidance is strong enough for an agent to select it correctly.

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