validate_vat

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

Minimal disclosure: describes validation of format but does not specify behavior on invalid input (e.g., error message vs boolean return), nor explicitly state it is a read-only operation. No annotations exist to compensate.

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?

Short and to the point, but slightly under-specified for a validation tool. Could include example or accepted format without adding verbosity.

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?

Given the tool's simplicity and presence of an output schema, the description adequately covers the core functionality. However, missing details about validation extent (format only vs. checksum) slightly reduce completeness.

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 description merely restates the parameter name 'vat' without adding meaning beyond the input schema. It does not specify expected format (e.g., country code prefix, length) or provide examples, despite 0% schema coverage.

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 VAT number format for EU countries, using a specific verb and resource. It distinguishes from sibling validation tools like validate_iban.

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?

No guidance on when to use this tool vs alternatives (e.g., validate_iban, validate_json). Lacks context on prerequisites or exclusions.

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