Check company on the VAT white list

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

Annotations already provide readOnlyHint, idempotentHint, destructiveHint, and openWorldHint. The description adds that it is a 'live query to the official KAS register' and describes the return values (VAT status and account-match result), providing context beyond annotations.

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?

Three sentences with no redundancy. Front-loaded with purpose, followed by usage guidance, then return info and nature. Every sentence adds value.

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 tool with two parameters and no output schema, the description covers purpose, usage context, return values, and live query nature. Annotations handle safety profile. No gaps identified.

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%, but the description adds functional meaning: it explains that the NIP is a Polish tax ID, that the account number is optional and for checking registration, and implies the optionality of the account parameter. This goes beyond the schema's basic type and pattern.

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 clearly identifies the tool's function: checking a Polish company's VAT status in the official white list register and optionally verifying a bank account. It distinguishes from siblings by focusing on VAT compliance, which is not covered by get_company, get_financials, or search_company.

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?

Explicitly states 'USE THIS before paying an invoice' and explains the tax consequence of paying over PLN 15,000 to an account not on the white list. This provides strong use-case guidance, though it does not explicitly mention when not to use it relative to siblings.

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