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

Annotations already declare readOnly, idempotent, non-destructive, closed-world, so the bar is lower. The description still adds meaningful behavioral context: results span current AND historical roles, include company status values (active/struck off/liquidating), and include a computed failure-rate analysis. It does not mention limits, pagination, or what happens for an unknown slug.

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?

Three dense sentences, front-loaded with the core capability, then coverage detail, then usage triggers. No filler and no repetition of the title.

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, return-value detail need not be restated, and the safety profile is covered by annotations. The description delivers what remains necessary: what data is included, its currency range, and when to reach for this tool.

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 single slug parameter is already fully documented as a person slug from shared.people. The trailing 'Uses person slug.' restates what the schema says, adding no format, resolution, or error behavior beyond it. Baseline 3 is appropriate.

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 ('Get full directorship history for any person') and names the data source (NZ Companies Register). It enumerates the scope well (NZX-listed + private, current and historical, status, failure rate). It does not explicitly differentiate itself from close siblings such as get_director_history or get_director_network, which the agent may conflate.

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?

Provides clear trigger conditions ('Use when asked about a person's full board network, private company roles, directorship workload, or company failure history'). No exclusions or named alternatives are given, so the agent still has to infer why this beats get_director_history for a given query.

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