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

With no annotations, the description carries the full behavioral burden. It usefully discloses the most important trait: the tool deliberately returns multiple candidates with their descriptions instead of a single answer, and it surfaces duty rates in the result. It does not cover authority/permissions, rate limits, pagination, or the meaning of the limit cap beyond what the schema already says.

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?

Two sentences, front-loaded with what the tool does and what it returns. The second sentence is slightly long but earns its place by explaining the deliberate multi-candidate design, which is the key behavioral fact an agent needs.

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 two-parameter read tool with no output schema and no annotations, the description covers intent, input form, and the nature of the return (candidate lines plus duty rates). It is nearly complete; only the limit behavior and any ordering/ranking of candidates are left unstated.

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 both parameters are already documented in structured form, establishing a baseline of 3. The description reinforces that 'description' is plain words but adds no new syntax, format, or constraint detail beyond the schema, and says nothing extra about 'limit'.

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?

The description gives a specific verb (search), a specific resource (the official US Harmonized Tariff Schedule), an input form (plain-language product description) and a return shape (candidate HTS lines with duty rates). It does not, however, differentiate itself from the siblings lookup_us_duty_rate and estimate_us_duty, which also deal with duty rates, so the agent must infer the division of labor.

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?

Usage is implied by the framing that 'classification is the hard part of importing', indicating this is the classification step rather than a rate lookup or a duty estimate. But no sibling is named, no when-not condition is given, and no prerequisite (e.g., you must obtain a code before estimating duty) is stated, so the routing decision is left to inference.

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