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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered by structured data. The description adds only the meaningful behavioral fact that results are limited to places with installers, and says nothing about result size, ordering, or whether the data is hierarchical (country→region→city).

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 with no filler or redundancy. It is as short as it can be while still stating the coverage constraint, though it does not structure the three levels of geography it returns.

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, non-destructive read with annotations covering safety and no output schema needed, the definition is nearly complete. The one gap is that it does not clarify the shape of the returned hierarchy (flat list versus nested countries/regions/cities), which an agent would want before displaying results.

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 no parameter meaning to convey and the baseline of 4 applies. The description correctly implies the tool is unfiltered and returns the full set of covered places.

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 names a specific verb (List) and specific resources (countries, regions and cities) and narrows scope to places that have heat pump installers, so an agent knows this is a geographic coverage lookup rather than a general place directory. It does not distinguish itself from the sibling list_* tools by name, but the resource is concrete enough to be unambiguous.

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 only implied: an agent can infer it should call this to discover which geographies are covered before searching listings. There is no explicit when-to-use versus search_listings or get_listing, and no statement of prerequisites or ordering of calls.

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