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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds value beyond that by disclosing the return shape (multiple candidate codes with descriptions and base duty rates) and that the call is not billed, which matters for planning.

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 short sentences, front-loaded with what it does, then the return value, then the routing rule and billing note. No filler and no repetition of the title.

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?

An output schema exists so return values need only be summarized, and the description does that. For a one-parameter read-only lookup this is nearly complete; it could add a hint about how specific the product description should be, which matters for classification quality.

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?

There is a single required parameter with 100% schema description coverage including concrete examples, so the schema does the work. The description adds nothing about how the query string is matched (keyword vs semantic, specificity expectations), so baseline 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 and resource: find the US Harmonized Tariff Schedule classification for a product, and names the return payload (candidate HTS codes with official descriptions and base duty rates). This clearly separates it from the landed_cost sibling, which is about cost rather than the code.

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?

"Use when the user wants the code itself rather than a cost" gives an explicit selection condition against the cost-oriented sibling, and the billing note clarifies it is not a charged duty lookup. It stops short of naming landed_cost directly or covering edge cases such as ambiguous product descriptions.

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