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

Annotations already declare readOnlyHint, idempotentHint, non-destructive and closed-world, so the safety profile is fully covered. The description adds no behavior beyond the data surface — no auth requirements, latency, or coverage caveats — and its field list largely restates the return payload that the output schema already carries.

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 sentences, front-loaded with the core action and followed by triggers; nothing is wasted. The enumerated return fields are slightly redundant against the output schema but do help an agent scan relevance quickly.

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 an output schema present, the description need not explain return values, and it correctly focuses on scope and triggers. The one gap is sibling disambiguation against get_auditor_red_flags, which an agent choosing between the two would need.

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?

There is a single parameter with 100% schema description coverage, so the schema already documents the NZX ticker format and examples. The description only implies the ticker via 'for an NZX company' and adds no syntax or validation detail beyond the schema, making the baseline 3 correct.

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 ('Get audit opinion history and red flags') scoped to NZX companies, and enumerates the returned content (auditor, opinion type, going concern, fees, risk signals). It does not, however, distinguish itself from the sibling get_auditor_red_flags, which appears to overlap heavily.

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 second sentence gives explicit trigger topics ('audit risk, auditor, going concern, audit opinion, audit fees, or auditor independence'), which is clear context for invocation. It stops short of naming alternatives or stating when NOT to use this tool versus the related auditor-red-flags sibling.

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