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 real behavioral context beyond that: a 50-item-per-call batch limit and the set of possible result statuses (in force, expired, amended/replaced). It does not mention auth needs, but the added context is meaningful.

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 purpose statement is front-loaded, but the description duplicates itself across English and Vietnamese (the closing Vietnamese sentence repeats the opening English one), so roughly half the content is redundant rather than additive.

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 read-only single-parameter lookup with no output schema, the description covers purpose, input format, batch limit, and the enumerable return states, which is sufficient for correct invocation. Only auth/permission context is absent.

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 a single parameter and 0% schema description coverage, the description carries the burden and does so well: it specifies soHieu is an array of strings, gives an example (["57/2022/NĐ-CP"]), caps it at 50 items, and explicitly warns a single string is rejected. These details go beyond the bare schema (which only enforces minItems 1).

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 ('Checks whether Vietnamese legal documents are in force by document number') and enumerates the outcome states (in force, expired, amended, replaced). None of the siblings (tax, procedures, HS codes) overlap, so the agent can route confidently.

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 purpose clearly implies when to use it and the description adds an input-shape constraint (array only, not a single string), but there is no explicit when-to-use/no-use guidance or named alternative. Usage is implied rather than spelled out.

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