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

With no annotations provided, the description carries the full burden. 'Returns' implies a read-only operation, and the enumeration of value categories adds useful context. But it does not disclose potential side effects, costs, or failure modes. For a simple list tool, this is adequate but not rich.

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 a single, front-loaded sentence that directly states the purpose and key output. It wastes no words and is perfectly scannable.

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 tool with no parameters and no output schema, the description is complete: it states the return content and enumerates the relevant categories. Given the sibling tools (comparison/query), this discovery tool is fully placed in context.

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?

There are zero parameters in the schema, so by the rubric the baseline is 4. The description does not need to elaborate on inputs, but it usefully clarifies that the output enumerates valid values for future parameters across the listed categories.

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 uses a specific verb ('Returns') and a clear resource ('all valid parameter values'), and enumerates the categories (ages, coverages, terms, genders, health classes). It distinguishes itself from sibling tools like compare_health_classes and query_rates by framing this as the prerequisite discovery tool.

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 phrase 'Call this first' provides explicit when-to-use guidance, making clear this is the initial discovery step. However, it does not mention when not to use it or name specific alternatives, so it lacks the full exclusionary guidance required for a 5.

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