validate_invoice_fields

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

No annotations are provided, so the description carries the full disclosure burden. It conveys that this is a read-only lookup and gives some output scope ('common EU requirements plus country-specific fields'), but says nothing about permissions, whether country coverage is complete, or how results are structured.

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 short sentences, front-loaded with the core action and followed by the output scope. Nothing is padded or redundant.

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 simple 2-parameter read-only lookup the description is adequate on inputs and rough output scope, but with no output schema and no sibling differentiation, an agent cannot confidently choose it over the several similar requirement-lookup tools.

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 description coverage is 100%, with countryCode documented as ISO 3166-1 alpha-2 and transactionType as an enum defaulting to B2B. The description adds no parameter detail beyond the schema, 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?

States a specific action and resource: checking which invoice fields are required per country, and distinguishes its scope with 'common EU requirements plus country-specific fields.' However, the name 'validate_invoice_fields' implies validating an actual invoice, while the description only describes a requirements lookup, creating a minor naming/behavior mismatch.

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 versus siblings like get_einvoicing_requirements, get_invoice_format, or get_en16931_info, which all sound related to invoice requirements. The agent must guess which of these to call for a given need.

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