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

Annotations already declare readOnlyHint, idempotentHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description adds no behavioral detail beyond purpose, such as whether a negative result means the account is unregistered versus the NIP being absent from the list, or any rate limits.

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?

Two short sentences, zero filler, with the core operation front-loaded and the compliance trigger as supporting context. Nothing needs trimming.

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?

The phrase 'check whether ... appears' implies a boolean outcome, which partially compensates for the absence of an output schema, but it does not describe what a whitelist match actually returns (e.g. account status or matching date). For a low-complexity two-parameter lookup this is adequate but leaves a real gap.

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 100%, with both parameters (10-digit NIP, 26-digit NRB without PL prefix) fully documented in the schema. The description only restates that a NIP scopes the lookup, adding no format or validation meaning beyond 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?

States a specific verb and resource: checking whether an NRB bank account appears in the VAT White List for a given NIP. That is distinguishable from sibling checks like sprawdz_nip or sprawdz_lista_nip, though the description never explicitly contrasts itself with sprawdz_lista_nip, which sounds adjacent.

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?

Gives a concrete use context: due diligence for payments above PLN 15,000, which ties invocation to a real regulatory trigger. It stops short of when-not-to-use guidance or naming an alternative tool for related checks.

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