getapi_validation_vat

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

With no annotations, the description carries the full burden and falls short: it does not say whether the call is read-only, whether it hits the live VIES service (with possible rate limits/timeouts), how an invalid VAT is reported (error vs. negative result), or what the response contains. Only the HTTP method and path are disclosed.

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?

A single front-loaded sentence with the verb and resource first and the endpoint appended as reference metadata. No filler or redundancy.

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 validation endpoint with no annotations, no output schema, and no parameter descriptions, the definition is incomplete: the agent cannot know the result shape (valid flag, company name/address), failure semantics, or whether this is a live external lookup with latency or quota implications.

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 0%, but the schema itself carries a strict pattern (^[A-Z]{2}[A-Z0-9+*]{2,13}$) that documents format constraints. The description adds meaningful scope by specifying 'EU VAT number (VIES)', telling the agent the number must be an EU/VIES-eligible identifier with country prefix, but gives no example or country-code guidance beyond that.

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?

States a specific verb (Validate), a specific resource (EU VAT number), and names the authority (VIES), plus the underlying endpoint POST /v1/validate/vat. An agent can tell it apart from the sibling validation tools (iban, email, dnsbl) by the VAT resource alone, though it never explicitly contrasts itself with them.

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?

There is no when-to-use guidance, no prerequisites, and no mention of alternatives among the many sibling validation tools. Usage is only inferable from the verb 'Validate', which is the minimum implied context.

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