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

Annotations already establish read-only, idempotent, non-destructive, closed-world behavior, so the bar is low. The description adds genuine context beyond that: the stable permanent_id format (NZX-P-NNNNNN) for cross-referencing, the FDC3 contactList format support, and the two underlying data sources merged into one timeline.

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?

Purpose is front-loaded in the first clause, with supporting details (sources, ID format, format support, usage triggers) following in a logical order. Five sentences is slightly dense but each contributes information; nothing is obviously redundant.

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-value documentation is not required. The description covers purpose, scope, data sources, identifier semantics, an interoperability format, and usage triggers, which is complete for a read-only lookup tool. Pagination and date-filter interaction details are the only notable omissions.

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 all six parameters with formats and allowed values. The description's mention of start/end dates, status, and committees loosely aligns with filters but adds no syntax or semantics beyond what the schema provides. Baseline 3 applies.

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 historical officer timeline for an NZX company") and scopes it precisely to "every director and executive who has ever held a role." It also clarifies the data provenance (director_appointments + management_team), which separates it from current-only siblings, though it never names those siblings directly.

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 explicit trigger conditions: "Use when asked about past leadership, board turnover, executive changes, or who used to run a company." This gives clear invocation context. It lacks an explicit "do not use for X, use Y instead" exclusion against close siblings like get_director_history or get_management_team.

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