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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered structurally. The description adds genuinely useful behavior not in annotations: the $0.002 USDC x402 cost, the unauthenticated first-call response, and the retry mechanism with specific header names or the params._meta payment path. It does not describe result shape or paging behavior, so it adds context but not full coverage.

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 returns and its exclusions before the payment mechanics. The 'Chinese field labels' fragment sits awkwardly mid-block and would read better next to the return-value sentence, but there is no filler.

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 does duty on returns by naming the fields (codes, general/special rates, footnotes) and their language. It also covers the auth/payment prerequisite that would otherwise block a correct call. Minor gap: no indication of result ordering, truncation, or what an empty match looks like.

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%, and both parameters carry bilingual descriptions including the English-keyword-or-HTS-code constraint and the limit bounds. The description adds no syntax or format detail beyond that, so the baseline of 3 applies. The 'Chinese field labels' note concerns output, not parameter meaning.

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: 'Find USITC HTS codes, general/special rates and footnotes,' which is concrete and actionable. It implicitly separates itself from the china_us_duty_layers sibling with 'Not total China-origin duties,' though it never names that alternative outright.

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?

Provides an explicit exclusion ('Not total China-origin duties or customs advice') plus a concrete operational sequence for the payment flow: call, receive x402 requirements, retry with X-PAYMENT or PAYMENT-SIGNATURE header. It stops short of naming a sibling tool to use instead for full duty stacks or legal guidance.

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