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

Annotations already establish the safe-read profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower. The description adds genuine value beyond them: it enumerates the returned fields (order number, initial volume, remaining balance, unit, validity window, status Open/Exhausted/Blocked, origins) and names HMRC's UK Integrated Online Tariff as the source.

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-loads the purpose and definition, then the authoritative-question framing, then the source and example. Dense but every clause carries information; the definitional aside on TRQs is the one part that is arguably optional for an expert agent.

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?

With no output schema, the description carries the return-shape burden and does so by listing exactly what each result contains plus the possible status values. Combined with the source attribution and worked example, an agent has everything needed to call and interpret this tool.

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 six parameters including defaults and limits; that sets the baseline at 3. The description's only parameter contribution is the embedded example call, which illustrates a filter combination but adds no semantics beyond what the schema states.

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?

Specific verb ('search') plus resource ('UK tariff-rate quotas'), and it goes further by defining what a TRQ actually is (limited volumes importable at reduced/zero duty). The uktariff_* siblings (commodity, heading, search) are implicitly distinguished by the quota/order-number/remaining-balance framing, so an agent can route correctly.

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?

Explicitly claims authority for concrete question types ('is the UK quota for X still open', 'how much of the New Zealand lamb quota is left'), which tells the agent when to reach for this tool. It does not name an alternative tool or a when-not-to-use condition, so it falls short of a 5.

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