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

Annotations already carry readOnlyHint=true and idempotentHint=true, so the safety profile is covered by structured data. The description adds one useful behavioral signal — 'this tool exposes them all' — indicating the response is the complete set of dimensions rather than a paginated or filtered subset. This is helpful context but not extensive.

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?

Three sentences, all earning their place: the main purpose is front-loaded, the workflow guidance follows, and the examples close it out. Nothing is wasted, and the structure is 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 zero-parameter, read-only list tool with an output schema present and safety annotations provided, the description covers everything an agent needs: what it returns, how to use it in context, and what to expect. Nothing material 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 and the schema is an empty object, so the baseline of 4 applies. There are no parameter semantics for the description to clarify, and it does not attempt to invent any.

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 (List) with an explicit resource (dimension type codes and human-readable titles) scoped to the WHO GHO API. It also clarifies the tool's role in the discovery workflow and gives concrete examples (COUNTRY, REGION, SEX), making it immediately distinguishable from siblings like who_list_indicators.

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?

Explicit guidance is given: 'Use this to discover valid dimension codes before calling who_list_dimension_values,' which pins down the tool's position in the expected workflow and names the downstream sibling. It lacks an explicit 'when not to use' statement, hence not a full 5.

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