eudr_verify_vies_vat

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

With no annotations, the description must carry the full burden of behavioral disclosure. It states that validation is real-time and via the VIES engine, but does not disclose what happens on invalid VAT numbers (e.g., returns a boolean, throws an error), whether the operation is read-only, or any network/rate-limit dependencies. This is a significant gap for a validation tool.

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, well-structured sentence that front-loads the core action and resource. There is no redundant wording or unnecessary detail, making it highly efficient.

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 tool has no output schema, and the description does not explain the return value or behavior on invalid input. For a simple validation tool, an agent would need to know whether the result is a boolean, a detailed report, or an error. The lack of this information leaves a critical gap, especially since no annotations provide safety or side-effect context.

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 input schema fully describes both parameters (vat_number and country_code) with clear explanations and examples. The description does not add any parameter-level information beyond what the schema provides, so the baseline of 3 applies.

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 'Validates' and a specific resource 'European Union B2B cross-border VAT numbers' via the official EU Commission VIES engine. It clearly distinguishes this tool from siblings like eudr_verify_plot, which verify different entities, and no other sibling handles VAT. The purpose is unambiguous.

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 implies the tool is for validating VAT numbers but does not explicitly state when to use it versus alternatives, nor does it mention any exclusions or contexts where it should not be used. Since no sibling tool directly competes, there is no need for alternative routing, but the description lacks guidance on prerequisites or typical use cases.

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