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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds useful behavioral content with no output schema present by stating what is returned (codes plus basic duty rates) and constraining input to Vietnamese keywords. However it says nothing about matching behavior, result caps, or the meaning of 'basic' duty rates.

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?

Front-loaded with the search action and its method in one sentence, with zero filler. The Vietnamese sentence duplicates the content bilingually, which is defensible for a Vietnam-domain tool but is technically redundant for an agent reading the English.

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 low-complexity, read-only, two-parameter tool the description covers purpose, input language, and return content, which is close to sufficient. It falls short because gioiHan's behavior (default value, max of 20, effect on results) is entirely undocumented anywhere, leaving an agent unable to reason about result limits.

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 carries the full burden for two parameters. It partially covers tuKhoa ('Vietnamese product-name keywords' and '(tiếng Việt)'), but gioiHan is never mentioned, and no length constraints or default-limit semantics are conveyed, so it fails to compensate for the coverage gap.

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 names a specific verb and resource ('Searches Vietnam HS codes') plus the input method ('by Vietnamese product-name keywords') and the return shape ('matching codes with basic duty rates'). This is clearly distinguished from a classification tool, but it never explicitly differentiates itself from close siblings like tra_cay_hs or phan_loai_hs, which an agent must choose between.

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 only implied: the agent can infer it should call this when it holds a Vietnamese product-name keyword rather than an existing code. There is no explicit when-to-use, no when-not-to-use, and no routing to alternatives such as tra_cay_hs or phan_loai_hs, which is a real gap given the number of HS-related siblings.

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