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

With no annotations the description carries the full burden, and it does disclose the metered cost ('1 point per returned record') and the returned fields, which is genuinely useful behavioral context. It omits pagination behavior, read-only confirmation, and any auth or error conditions for a tool whose schema exposes start_page/max_items.

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 compact sentences, front-loaded with the resource and scope before the cost note. No wasted prose, though it is minimal enough that the concision borders on under-specification.

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 usefully enumerates the return payload (date, type, file links) and the pricing model. The main gap is pagination behavior for the exposed page/limit params, but nothing essential for calling it correctly is missing.

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%, so the schema already documents company, max_items and start_page, establishing the baseline of 3. The description adds no parameter-level meaning beyond what the schema provides.

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+resource: documents filed by one New Zealand company, with the source (Companies Register) and the returned fields (date, type, file links). This clearly separates it from run_nz_companies and run_nz_companies_search, though it never names those siblings explicitly.

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?

Implies usage by saying documents are 'filed by one New Zealand company', which signals a single-company lookup requiring a registration number. However, it offers no explicit when-to-use, no prerequisites (e.g. resolve the number via run_nz_companies_search first), and no exclusions versus sibling document/company tools.

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