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

Annotations already cover readOnly, idempotent, non-destructive and closed-world semantics, so the bar is lower. The description adds genuinely new behavioral context: every result carries an unofficial-copy notice the agent must show the end user, plus a breakdown of what the line contains (designations, MFN duty, preferential regimes, restrictions, relief codes).

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 tight sentences, front-loaded with the verb and resource, then the two input modes, then the notice obligation. No filler or redundancy.

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 the work of describing the return payload (designations, duties, preferential regimes, restrictions, relief codes) and adds the mandatory unofficial-copy notice. The only real gap is the behavior of the lang parameter, which is left implicit.

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 coverage is 50%: hs8 is fully documented in the schema and the description largely restates it (dots allowed, prefix behavior). The lang enum has no schema description, and the description only hints at it via 'designations in FR/DE/IT/EN' without stating that lang controls the output language. Baseline 3 is appropriate given partial coverage.

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 (Swiss customs tariff / TARES), and clearly distinguishes itself from siblings cross_walk and kyc_check, which are unrelated domains. An agent can identify the operation and scope 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?

The description explicitly explains the two usage modes — an 8-digit number returns one full line, a 2- to 7-digit HS prefix lists the Swiss lines under it — which tells the agent how to invoke it correctly. It does not name alternatives or exclusions, but the sibling tools are in different domains so that is less critical.

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