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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the description correctly focuses on behavior instead: freshness, that the result includes source revision and date, and the availability caveat for complex/stale codes. It does not cover auth requirements or rate limits, leaving a small gap.

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?

Three compact sentences, front-loaded with the purpose before the caveats and routing. Slightly jargon-dense ('excluded layers', 'MFN general duty field') but no sentence is 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?

No output schema exists, so the description carries the burden of describing returns, and it does so partially (source revision, date, excluded layers) while clearly bounding the numeric meaning of the rate. The remaining gap is only the exact response shape.

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?

With only one parameter and 100% schema description coverage (pattern, dot-optional formats, and the 'does not classify product descriptions' note), the schema does the heavy lifting. The description adds no hsCode-specific syntax or format detail beyond that, so the baseline of 3 applies.

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 (look up) and resource (US HTS / MFN general duty rate) and immediately scopes it as 'base-only', which distinguishes it from the sibling review_import_duty tool. An agent can tell the two apart 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?

Explicitly names the alternative and the selecting condition: 'use review_import_duty for quantity-based duties.' It also gives a strong when-not rule ('never treat this as the final import tariff') and flags that complex or stale rates may be unavailable.

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