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), and the description adds genuinely new behavioral detail: only market-value category A sales are counted and the geographic scope silently widens to the whole street when postcode coverage is thin. It does not say what is returned when no suitably sized sales exist, which is the main remaining unknown.

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?

Three short sentences, front-loaded with the data source and metric, then the scope rule, then the sale-type filter. No restatement of the title and nothing superfluous.

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 does the necessary work of naming the return values (price per m² and per ft², by year) and flagging the `scope` field, which is what an agent needs to interpret results. The only gap is the empty-result / insufficient-data case.

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 single `akey` parameter is documented in the schema as a hex address key from search_addresses. The description only indirectly implies that the key identifies 'one home' and adds no format or sourcing detail beyond the schema, so baseline 3 applies.

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 resource (recent Land Registry sales joined to EPC floor area for one home) and the exact metric produced (pounds per square metre and per square foot, by year). An agent can tell it is the per-area-price tool rather than a general price or area tool, though no sibling is named 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?

The definition explains the internal scope rule (own postcode when it has enough sized sales, otherwise the whole street) and that the `scope` field reports which was used, which orients the agent. However, it gives no guidance on when to choose this over price_check, price_trends, or area_overview, so the choice among siblings is left to inference.

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