lookup_vat_be

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

No annotations are provided, so the description carries full burden. It discloses the output fields (legal name, address, etc.) and the optional auth. But it does not mention error handling, rate limits, or what happens if the number is not found. Basic transparency is present but could be more comprehensive.

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?

Four sentences, each serving a distinct purpose: purpose, input flexibility, output description, optional authentication. No wordiness, well structured, and front-loaded with the core action.

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 lookup tool with one parameter and an existing output schema, the description covers key aspects. It could mention error cases or prerequisites, but given the simplicity and the presence of an output schema, it is sufficiently complete.

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?

The schema already describes the parameter, and the description adds valuable formatting details (prefix, dots/spaces) beyond the schema. Schema coverage is 100%, so baseline is 3; the extra formatting guidance raises it to 4.

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 states 'Look up a Belgian enterprise number' against a specific database (BCE/KBO). It uses a specific verb and resource, and distinguishes well from sibling tools like generate_invoice_be or validate_invoice_be which have different purposes.

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 description provides input formatting guidance (with/without prefix, dots/spaces) and mentions optional environment variable for authenticated access. However, it does not compare to sibling tools or specify when to use this vs. check_peppol_participant_be. No explicit when-not or alternative instructions.

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