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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safe-read and external-live-data profile is covered. The description adds genuinely useful behavioral context: the result set is restricted to company-level data with no person records. It says nothing about rate limits, result caps beyond the limit param, or error behavior when an ID is not found.

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?

One tightly constructed sentence with the action and scope front-loaded, followed by a short scope-limiting clause. Every phrase carries information; there is 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?

With no output schema, the description helpfully enumerates the returned fields and the company-only limitation, which is enough for an agent to call and interpret the tool. The remaining gap is minor: it does not describe empty-result or not-found behavior, but for a read-only lookup that is not essential.

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%: each of the four parameters (id, name, limit, country) is already documented in the schema, including the id pattern, the NO/FI enum, and the id-over-name precedence. The description adds no syntax or format detail beyond the schema, so the baseline 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 verb (look up) and resource (companies in the Norwegian and Finnish company registers) plus the two lookup keys (registration number or name). It also enumerates the returned attributes (name, legal form, industry, address, registration date, status), so an agent knows exactly what this tool delivers. No sibling covers company-register lookups, so no differentiation is needed.

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 description implies usage by naming the two lookup paths ('by registration number or name') and scopes out non-company data ('Company-level data only, no persons'). However, it gives no explicit when-to-use context, prerequisites, or precedence between id and name lookups, so the routing guidance is implied rather than stated.

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