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; the description usefully adds that a lookup with an opinion number returns the full text plus a reference Vietnamese translation, which partially compensates for the missing output schema. It says nothing about coverage, truncation, or behavior when the HS code has no entry.

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 compact sentences, front-loaded with the resource and selector, and the bilingual Vietnamese line mirrors the English rather than adding new content. Efficient, if slightly redundant by design for a Vietnamese-facing tool.

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, no-output-schema tool with minimal annotations, the definition covers the core lookup but leaves the ordinal parameter, empty-result behavior, and the HS-code/opinion-number relationship unexplained. Adequate but with clear gaps.

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 0%, so the description must carry the burden. It labels maHs ('mã HS') adequately, but the second parameter thuTu (integer 1-999) is never explained - it is unclear whether 'opinion number' refers to thuTu or is a derived value, and no format or selection rule for it is given.

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 ('looks up') and a precise resource ('WCO classification opinions (Compendium)') with the selector ('by HS code'), so the purpose is unambiguous. It does not, however, distinguish itself from near-neighbors such as tra_chu_giai or tra_tien_le, which also retrieve explanatory/opinion-like content.

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 'by HS code / with an opinion number' phrasing implies the retrieval workflow, so usage is inferable, but there is no explicit when-to-use or when-not-to-use guidance and no sibling is named as an alternative. Given the crowded tra_* family, this leaves real routing ambiguity.

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