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

Annotations already cover read-only, idempotent, non-destructive, closed-world behavior. The description adds the important behavioral caveat that the figure is an estimate rather than exact, and explains the two coverage components; return format is left to the output schema.

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?

The description front-loads the definition, then provides a usage example and an estimate caveat in compact form. The parenthetical local-authority note is useful but makes the first sentence dense.

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 one-parameter read-only tool with an output schema and rich annotations, the description supplies the conceptual meaning of coverage and the necessary estimate caveat. It leaves sibling routing implicit, which is a minor gap.

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 schema already documents the area parameter with town, outcode, and postcode examples. The description adds only that the area is also resolved to its local authority; it does not add syntax or validation detail beyond the 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?

The description states a specific metric: an estimate of homes-for-sale coverage plus estate-agent participation, for a town, outcode, postcode, and local authority. That clearly distinguishes it from a generic area-statistics tool, but it does not explicitly name or contrast with siblings such as area_stats.

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?

It gives an explicit use case — communicating how complete answers are—and a required framing rule to always call the figure an estimate. It does not state when to choose this over area_stats or other siblings, so alternative routing is only implied.

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