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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, not open-world), and the description layers on genuinely non-structured behavior: per-item outcomes (ok | not_found | error) returned in input order, partial-failure billing semantics ('charged per property answered — the sum, never more'), a 5-credit cost, and a geographic restriction. Only pagination/rate details are absent.

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?

Four short sentences, front-loaded with what the tool does and how it is charged, then constraints and prerequisites. No filler, no repetition of the title or schema.

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 batch tool with an output schema, the definition supplies everything an agent needs: cost, billing model, regional scope, key format, prerequisite chain, and partial-failure semantics. Return values need not be re-explained since an output schema exists.

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 `uprns` array, so the description must carry the meaning — and it does, clarifying the key is a UPRN (not an address), that it is an integer identifier, and how to obtain one via `address_resolve`. It does not state the array's ordering/cardinality contract explicitly, but 'in input order' and 'up to 100' cover most of it.

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 and resource (risk report) plus the batch cardinality (up to 100 properties in one call), and names the singular sibling `property_risk_report` it wraps, so an agent can separate it from that tool without opening either 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 a concrete prerequisite chain: `address_autocomplete` (free) to narrow, then `address_resolve` to obtain the UPRN this tool is keyed on, and notes 'UK only'. It stops short of an explicit when-not-to-use rule (e.g. use the singular tool for a single property), but the batch-vs-singular framing in the first clause implies it.

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