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

With no annotations, the description carries the full burden and does well: it discloses the paid x402 model ($0.004/call, USDC on Base) and the payment_signature handshake implied by 'omit to receive payment requirements'. It also warns that classification is advisory. It does not describe rate limits, error modes, or a return shape, so it is not fully exhaustive.

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 dense sentences, front-loaded with purpose then routing/caveats then pricing. Every sentence carries information, though the tariff-source enumeration in sentence two is somewhat heavy for the retrieval value it adds.

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 5-param tool with no output schema and no annotations, the description covers scope, sources, payment model, and the advisory caveat on classification. The main gap is return-value shape beyond 'candidate codes' for keyword mode, which an agent would otherwise need to discover at runtime.

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 baseline is 3. The description restates the code-vs-keyword distinction and ties origin to preferential rates, which the schema already covers, adding little new syntax or format detail. Payment semantics beyond the schema's field description are the only genuine addition.

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 (find HS/commodity code and import duty) with explicit geographic scope (UK or US) and names the underlying data sources (UK Global Tariff, UK Trade Tariff, USITC HTS). An agent can tell exactly what this tool 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 when-to-use contexts: quoting landed cost, or preparing a UK/US customs entry. Also sets expectations that keyword search returns candidates and that final classification remains the importer's responsibility. No sibling tools exist, so no alternatives needed, but it stops short of stating when NOT to use it.

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