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

With no annotations, the description carries the full burden. It discloses the data source and the shape of the result (direct/indirect ownership structures, control nature) and adds anti-hallucination rules, but says nothing about auth requirements, rate limits, or behavior when no owners are registered.

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?

Front-loads the purpose and what is returned before the rules, with no filler sentences. The RULES block is slightly boilerplate (generic anti-hallucination guard) but does earn its place by warning against fabricating ownership chains.

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 one-parameter read lookup with no output schema or annotations, the description adequately covers source, return content, and input prerequisites. Missing only edge-case behavior (company not found, no registered owners), which is minor here.

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% and the single identifier parameter already documents OIB or MBS, so the description adds no format or syntax detail beyond the schema. The 'interview the user first' note is the only extra parameter-related guidance, which lands at the baseline 3.

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 (retrieve) and resource (registered true owners and authorized representatives) for a Croatian company, and names the source registry (FINA RSV). This clearly separates it from generic siblings like get_company_overview, but it never names or contrasts with the closest sibling search_true_owners, leaving the boundary implicit.

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?

Gives one conditional rule ('If identifier is missing, interview the user first'), which is useful but narrow. It never says when to prefer this over search_true_owners or get_company_overview, so the choice between siblings is left to inference.

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