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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint=false, so the safety profile is covered. The description adds the non-obvious behavioral fact that only places with auction houses/platforms are returned, but says nothing about ordering, pagination, or result size.

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 sentence with no filler, and the scoping constraint comes in the same clause as the resource, so it is front-loaded and unambiguous.

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 enumeration with annotations covering safety and no output schema, the description supplies enough to call the tool correctly. The only gap is what form the returned geography list takes and whether it is flat or nested.

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, so the schema carries nothing that needs explaining; baseline 4 applies. The description correctly implies a full unfiltered enumeration rather than a queried subset.

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?

States a specific verb ('List') and resource ('countries, regions and cities') with a meaningful scope qualifier ('that have auction houses and platforms'). An agent can distinguish it from get_listing or search_listings, though it never names a sibling explicitly.

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?

Usage is implied: use it to discover which geographies are covered before filtering searches. There is no explicit when-to-use statement, no mention of alternatives like list_sources or list_categories, and no exclusions.

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