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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered. The description adds the data provenance (Companies Office register) and the fact that the result set includes NZX director matches, but says nothing about freshness, update cadence, or completeness limits of the register snapshot.

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, zero filler: the first defines what is returned and from where, the second gives invocation triggers. Front-loaded with the core action and appropriately sized for a no-parameter tool.

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?

An output schema exists, so return values need not be explained, and the annotations carry the safety profile. For a zero-parameter, read-only list tool the description supplies everything an agent needs: what it returns, its source, and the phrasing that should trigger it.

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?

The tool takes zero parameters, so there is no parameter semantics to document and the baseline is 4. The description correctly implies a fixed, unfiltered full-list retrieval rather than implying any hidden filtering options.

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 the full list of prohibited/banned directors') and names the authoritative source ('Companies Office register'), which distinguishes it from siblings like get_directors, get_director_risk, or get_officer_history. The added scope note about cross-matching current NZX directors makes the returned dataset unambiguous.

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?

Explicit trigger conditions are given: 'Use when asked about prohibited directors, banned directors, disqualified persons, or director fitness checks.' That covers when to use it well, but no alternative or exclusion is named (e.g. when to prefer get_director_due_diligence or get_kyc_screening instead), so it stops short of full routing guidance.

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