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

Annotations already establish that this is a safe, read-only, idempotent operation. The description adds substantial behavioral detail beyond annotations: how area statistics are computed, fallback geography, sample-size thresholds, null UPRN handling, withheld facts, and candidate behavior for ambiguous fragments.

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 is front-loaded with the main output, but it is a dense wall of text with long semicolon-separated clauses and parentheticals. Most details earn their place, yet the lack of structure makes it harder to scan than it needs to be.

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?

Despite the tool's complexity and the presence of an output schema, the description covers the key behavioral edges an agent needs: area-only valuation stance, sample thresholds, hidden homes, null and withheld facts, and ambiguous-fragment handling. Nothing critical appears to be missing for correct invocation.

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%, so the schema already documents property_ref, but the description adds useful semantics about fragment ambiguity, asking which home, and passing its addressId. It also clarifies that homes without a linked UPRN are reachable and will carry uprn null.

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 verb and resource: recorded sales for one London home plus today's area price statistics. It distinguishes the scope from sibling area tools by emphasizing 'Area statistics only: never say what the home is worth; describe the area.'

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 clear invocation context: accepts a UPRN, an address id from search_places, or a fragment, and explains that ambiguous fragments return candidates rather than choosing a home. It also states key exclusions such as below-five-sales suppression and hidden homes, though it does not explicitly route agents to sibling alternatives like get_nearby_sales_summary or get_area_metric.

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