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

Annotations already declare the safe read profile (readOnly, idempotent, non-destructive, not open-world). The description adds genuinely new behavioral context: newest-first ordering, England & Wales geographic restriction, and that the call is free. Return format is covered by the output schema, so its absence here is fine.

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 tight sentences with zero waste, front-loaded with the core verb+resource and ordering, followed by coverage, cost, and the prerequisite workflow. Every sentence earns its place.

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 single-parameter read tool with rich annotations and an output schema, the description covers purpose, geography, cost, ordering, and input sourcing. Only minor gaps remain (e.g., pagination/record limits), which are partly implied by 'All ... records'.

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 0% for the single required 'uprn' parameter, so the description must carry the load. It adds real value by telling the agent where to source a UPRN (address_resolve) and that an address is not accepted, but it does not describe the parameter's type or format. Partial compensation for a 0% coverage 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?

States a specific resource and scope: 'All HMLR Price Paid records joined to this UPRN, newest first.' It also explicitly names the keying dimension ('Keyed on a UPRN, not an address'), which distinguishes it from address-oriented siblings like address_by_uprn.

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?

Gives explicit prerequisite routing: call address_autocomplete to narrow, then address_resolve to obtain a UPRN. This is clear 'how/when to get the input' guidance. It does not, however, contrast against alternative transaction tools like property_history or subject_transaction_anchor, so it stops short of full alternative selection guidance.

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