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

With no annotations, the description carries the full burden. 'Check' strongly implies a read-only lookup and the data domains are named, but the description omits supplementary behavioral details such as response shape, data freshness, availability of KRS fields, or any access limitations.

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 description is a single concise sentence that front-loads the operation and includes the useful Biała Lista alias. There is no filler or redundancy.

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 one-parameter lookup, the description is suitably complete: it states what is checked, the input key, and the data category returned. Although there is no output schema, the returned information is sufficiently scoped for an agent to invoke the tool correctly.

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%: the single nip parameter already has a clear description ('10-digit Polish NIP (tax ID)'). The tool description adds only that the NIP belongs to a Polish company, which is marginal and does not meaningfully improve on the schema.

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 uses a specific verb ('Check') and identifies a clear resource: VAT status from the Polish White List plus KRS data, keyed by NIP. It also differentiates itself from siblings that check by REGON or cover EU VIES status.

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 intended use is implied through 'Polish company' and 'Biała Lista', but the description does not explicitly say when to prefer this tool over alternatives like sprawdz_vies, sprawdz_regon, or sprawdz_lista_nip. No exclusions or alternative routing are provided.

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