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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description adds meaningful context beyond them: the authoritative data source (official FSA data), the Scottish rating scheme difference (Pass/Improvement Required instead of 0-5), and cost/billing (USDC per call, x402 or prepaid, free trial). It does not mention rate limits, pagination beyond 'limit', or result-count behavior.

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 what is returned, then search keys, then source and pricing. Dense but every clause carries information; the pricing sentence is slightly tangential but relevant for a paid x402 tool.

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?

An output schema exists, so return-value explanation is not required, yet the description helpfully enumerates the returned fields. Combined with the source, coverage, and pricing disclosure, an agent has enough to call it correctly; only edge behavior (no results, rate limits) is unaddressed.

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 100%, so the schema already documents all four parameters with examples (e.g. 'SW1A or SW1A 1AA'). The description mirrors the same search keys without adding syntax or matching semantics (partial vs exact, name normalization). Baseline 3 is appropriate.

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 (UK food hygiene ratings from the FSA), the entity types covered (restaurants, takeaways, shops, food businesses), and the fields returned. An agent can tell this apart from uk-postcode or uk-house-prices. The retrieval verb is only implied through 'Search by name/postcode/address' rather than stated outright, keeping it just short of a 5.

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?

The description lists the three supported lookup keys (name, postcode, address), which implies when the tool applies. It never states prerequisites (none required), when to prefer an alternative, or what to do if no location/name is known, so usage is inferred rather than guided.

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