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

With no annotations, the description carries the full load and does well: it discloses the upstream source (National Tax Service), a 30-minute sync cadence, the cost and payment rail ($0.002 USDC via x402 on Base or Solana), and the 400-without-charge behavior on bad check digits. Missing rate limits or failure modes beyond the check-digit case keep it from a 5.

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?

Information-dense and front-loaded: use case first, then input, output, data provenance, example, and price. The terse 'Input:/Output:/Data:/Price:' shorthand is slightly compressed but every sentence carries actionable content.

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?

There is no output schema, so the description enumerates the returned fields (status enum, VAT type, closure date, tax-type change, e-invoice dates, companyId), which is exactly what's needed. Input, output, source, freshness, and cost are all covered for a one-parameter tool.

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 100%, so the baseline is 3, but the description adds genuinely new detail: the 1-20 count range, hyphen tolerance, and a working example URL. That extra guidance about what the string may look like is useful beyond the schema's '10 digits, comma-separated'.

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 states a specific verb and resource ('check that a South Korean business is still operating') plus the data source (NTS), which is far more than a restatement of the name. It does not, however, distinguish itself from the sibling kyb_check, which an agent plausibly could confuse with this tool.

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?

It gives concrete situations for use: before paying, contracting, or onboarding, and names the KYB/invoice-check use cases. It stops short of stating when NOT to use it or pointing to kyb_check as the alternative, so this is clear context without exclusions.

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