validateEuVatNumber

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

Annotations indicate 'destructiveHint: true' and 'openWorldHint: true', suggesting side effects or external dependencies, but the description describes a read-only validation operation. This contradiction undermines transparency, and no additional behavioral context is provided 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?

The description is a single clear sentence that directly conveys the tool's purpose without extraneous text, achieving appropriate conciseness.

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?

Despite clear parameters, the description fails to address the contradiction between its stated read-only nature and the annotations indicating destructiveness, nor does it clarify return values or external dependencies, leaving significant gaps for a validation tool.

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%, and both parameters are adequately described in the schema. The description adds no extra meaning or constraints beyond what the schema already provides.

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 the tool validates an EU VAT number against the official VIES database, specifying the verb 'Validate' and the precise resource, distinguishing it from the sibling tool 'searchTaxGuides' which likely handles tax documentation.

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 a validation context but provides no explicit guidance on when to use or avoid this tool compared to alternatives, missing exclusions or prerequisites.

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