Validate Tax ID

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

With no annotations, the description carries the full behavioral burden and falls short. It does not say whether validation is a pure format/checksum check or a live registry lookup, what happens with an unsupported country, whether it throws or returns a boolean/status, or whether auth is required. Only the supported-region list adds any behavioral context.

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?

Two compact sentences with no filler, and the core action is front-loaded. It could be tightened slightly, but nothing is wasted.

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?

With no output schema and no annotations, the description must explain what a validation result looks like and what unsupported or invalid input produces, and it does neither. For a pure-input validation utility whose only value is its verdict, this is a substantial gap.

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%, so both parameters are documented in the schema and the baseline is 3. The description adds real meaning for the country parameter by enumerating the supported jurisdictions (EU, UK, Switzerland, Australia, New Zealand, Canada/Quebec), which effectively communicates the valid range of country inputs.

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 gives a specific verb (validate) and resource (tax identification number) and enumerates the identifier types covered (VAT, GST, ABN). It does not explicitly differentiate itself from siblings like calculate_tax, but those are clearly different operations, so the tool 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?

There is no guidance on when to call this tool versus the siblings — e.g. whether it should be used as a preflight check before create_invoice or create_contact. Usage is only implied by the tool name, with no conditions, prerequisites, or alternatives named.

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