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

Annotations already mark it read-only, idempotent, and non-destructive, and the description adds substantive behavior: UK-only scope, 25-credit cost, null-field omission, variable field counts, and provenance source/confidence fields. That is meaningful context beyond the annotations.

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 resource and tier structure, then adds only high-value details: field count/null behavior, provenance, UK/cost, and UPRN acquisition. No sentence is wasted.

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 tool with an output schema and clear annotations, the description covers the essential call context: what the record contains, variable returns, cost, geography, and how to get the key. Nothing critical is missing.

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 schema only declares an integer 'uprn' with 0% description coverage; the description compensates by clarifying it is keyed on a UPRN, not an address, and by naming the free address_autocomplete → address_resolve path to obtain one. It still does not define UPRN format or validation, so it does not fully compensate for the schema gap.

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 resource and scope: a full property record keyed on a UPRN, with enumerated tiers and up to ~300 fields. It distinguishes from the address chain by saying it is not address-keyed, though it does not explicitly contrast with property_summary or property_report.

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 a clear workflow for obtaining the required identifier: call address_autocomplete (free) to narrow, then address_resolve to get a UPRN. It also discloses the 25-credit cost, but does not explicitly say when to prefer property_summary/property_report or when not to use this tool.

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