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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description does add one genuinely useful behavioral fact — the result set is restricted to places with marine contractors, not all geography — but says nothing about ordering, pagination, or the shape of each entry.

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?

One short sentence, front-loaded with the verb and resource, with the scoping qualifier at the end. Every clause earns its place and there is nothing to trim.

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 no output schema, the description is the only place to learn what a returned 'place' looks like (name vs. ID, hierarchy, grouping). It establishes the domain but not the return shape or how the values should be fed into sibling filters, leaving a real gap for a discovery tool.

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 there is nothing for the description to disambiguate; baseline is 4. The sentence correctly implies the call needs no input, matching the empty schema.

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 a specific resource ('countries, regions and cities'), plus a meaningful scope qualifier ('that have marine contractors'). It separates itself from search_listings and get_listing by resource type, though the distinction from list_categories/list_sources is only implicit in the noun.

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?

There is no when-to-use or when-not-to-use guidance and no sibling is named. The agent must infer that this is a facet/discovery tool used to obtain valid place values before calling search_listings; that inference is left entirely to the reader.

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