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

No annotations exist, so the description carries the full burden. It usefully enumerates the returned fields (legal name, ID, status, address, VAT ID, activity code, source link), which substitutes for the missing output schema, but says nothing about read-only nature, permissions, rate limits, or what happens when country is omitted.

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?

Four compact lines, front-loaded with the core action before the country enumeration and return list. The dense country code list earns its place, though it slightly dominates the description relative to the two undocumented parameters.

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 annotations and no output schema, the description covers the essentials an agent needs: the lookup key, the supported registries, and the returned fields. Remaining gaps are the meaning of an empty country default and limit/pagination behavior, which are minor for a read-style lookup.

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 0%, so the description must compensate. It does this well for 'country' by enumerating FR/NO/FI/CZ/PL/EE plus ISO codes and 'LEI', but adds nothing for 'query' (name vs number matching behavior) or 'limit' (default 3, paging semantics), leaving two of three parameters undocumented.

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 and resource ('look up a company in official European business registers') and scopes it by input type (name or registry number). It is clearly a registry lookup rather than a verification, which distinguishes it from verify_vat/kyb_check in spirit, though it never names a sibling to make the boundary explicit.

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 final sentence gives three concrete use cases (confirm existence/active status, find a registry number, map a name to a VAT ID), which is clear context for selection. It stops short of naming alternatives or exclusions, e.g. when to prefer verify_vat over mapping a name to a VAT ID.

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