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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuine value beyond that: it discloses the concrete response fields (name, status, legal form, founding date, address, VAT) and a data caveat — VAT only "where published" — plus register-specific fields.

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 tight sentences with the core question front-loaded, followed by a compact list of registers and returned fields. No filler; every clause carries information.

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, the description correctly spends its space describing returned fields and register coverage. The notable omission is how name searches behave when multiple companies match and what limit does — relevant for a tool that accepts a name plus a result cap.

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 50%: number and name carry their own descriptions, while limit has none and country only an enum. The description partially compensates by clarifying the two lookup modes and mapping each country to its register, but it says nothing about the limit/result-set behavior for name searches, which is the main semantic gap.

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 states a specific verb and resource — verifying whether a company is "real and alive" via its national register by number or name — and enumerates the four covered registers (Brønnøysund, SIRENE/RNE, ARES, PRH). It does not explicitly contrast itself with siblings like vat_check or lei_lookup, so it falls short of a 5.

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 opening question "Is this company real and alive?" implies the verification use case, but there is no explicit when-to-use/when-not guidance and no mention of the alternatives in the sibling set (lei_lookup, vat_check, sanctions_screen) that could also answer company-identity questions. Usage is implied rather than instructed.

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