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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds real behavior beyond them: the catalog includes listing counts per country and that names are resolved in the requested language, which an agent cannot infer from annotations.

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?

A single front-loaded sentence that lists the catalog contents with no filler. Every clause carries information an agent needs.

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, the description needn't explain return shape, and it adequately covers what the catalog contains and how locale affects it. It stops short of saying when this catalog must be consulted, a minor gap for a lookup tool with one optional parameter.

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% and the enum plus per-parameter description already document locale, so baseline is 3. The description slightly exceeds that by confirming the locale governs the language of the returned names, tying the parameter to observable output behavior.

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 clear resource (the set of values accepted by search_listings) and enumerates its contents (countries with counts, property types, transaction types, features, sort orders, currencies). It implicitly distinguishes itself from search_listings by describing itself as the catalog that feeds it, though the verb is not explicit.

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 'Values accepted by search_listings' implies this tool is called to discover valid filter inputs before searching, which gives usable context. However, it never states when to call it versus simply calling search_listings, nor any exclusions or prerequisites (e.g., must fetch first).

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