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

Annotations already cover the safety profile (read-only, idempotent, non-destructive, closed-world), and the description adds substantial context beyond them: null fields are omitted so output size varies by site, provenance carries <field>_source and <field>_confidence siblings, it is UK-only, and it costs 25 credits. Disclosing cost and the omitted-null behavior materially changes how an agent should budget and parse the call.

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?

Front-loaded with the core purpose, then progressively adds tier detail, return-shape caveats, scope, cost, and workflow. Every sentence earns its place and there is no filler despite the density.

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?

The output schema exists, so return values need not be re-documented, and the description still usefully signals the tiered ~300-field shape and the provenance sibling fields. Combined with scope, cost, and the UPRN workflow, an agent has everything needed to select and invoke this correctly.

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 description coverage is 0% for the single uprn parameter, so the description must carry the load. It clarifies that the key is a UPRN rather than an address and routes the agent to address_autocomplete/address_resolve to obtain one, which is more than the bare integer schema provides. It doesn't give the UPRN format or range, keeping it short of a 5.

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 verb+resource: a full property record for a UPRN, explicitly broken into named tiers (identity, property, energy, building, etc.). The 'up to ~300 fields' scope distinguishes it from lighter siblings like property_summary, and it makes the UPRN key explicit. An agent can identify what this returns without opening the schema.

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 prerequisites and workflow: it is keyed on a UPRN not an address, so call address_autocomplete (free) to narrow, then address_resolve. It also notes UK-only scope and a 25-credit cost, which are real selection constraints. It does not, however, contrast against analogous siblings such as property_report or property_summary, so the when-not-to-use case is left implicit.

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