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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safe-read profile is covered. The description adds format tolerance detail but discloses nothing further about behavior — no indication of what rate categories are returned, whether lookup is exact vs fuzzy, or failure modes.

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?

The English sentence is front-loaded and efficient, but the Vietnamese text is a verbatim translation that roughly doubles length without adding information for a tool-selection agent. One language would have sufficed; the duplication dilutes conciseness.

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 simple two-parameter lookup with no output schema, the description covers input format adequately and annotations cover the safety profile. However, it says nothing about the shape or content of the returned duty information, which is a real gap when no output schema exists to fill it.

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?

With 0% schema description coverage, the description must carry parameter meaning, and it does: maHs accepts 4–8 digits with dots or spaces tolerated, and xuatXu is a 2-letter country code. That compensates well for the bare schema, though it doesn't say how dots/spaces are normalized or what happens with an invalid country code.

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+resource ('looks up Vietnam import duty rates') scoped to an HS code, which is a distinguishable function from sibling tools like tra_tien_le or tra_thu_tuc_nhap_khau. It does not explicitly name or contrast any sibling, so it lands just short of a 5.

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 implies its use case (checking duty rates for a given HS code) but never states when to pick this over alternatives such as tra_tien_le or tra_cay_hs, nor any exclusions or prerequisites. Usage is inferable but nothing is spelled out.

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