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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description's job is to add context. It delivers that by disclosing the reconstruction methodology and the four categories of output (direct holders, nominee breakdowns with identified fund managers, fund holdings, substantial holders), which tells the agent this is an aggregated/derived view rather than a live feed.

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 tight sentences: purpose first, methodology second, return contents third. No filler and the scope ('for an NZX issuer') is front-loaded.

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 annotations covering safety and an output schema present, the definition is nearly complete for a single-parameter read tool. The only gap is the absence of routing guidance against the many ownership-adjacent siblings, which is minor given the distinctive 'beneficial/reconstructed' framing.

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?

Single ticker parameter with 100% schema description coverage and a concrete example ('FPH', 'SPK', 'AIR'), so the schema carries the semantics. The description adds no further parameter detail, which is the expected baseline when coverage is complete.

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 reconstructed beneficial ownership) scoped to an NZX issuer, and the methodology clause ('cross-references top-20 shareholder registers with fund manager holdings and custodian mappings') makes clear this is a derived analysis rather than a raw register dump. It distinguishes itself conceptually from siblings like get_shareholders and get_substantial_holders, but never names them.

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?

Usage is implied rather than stated: the emphasis on identifying 'who is behind nominee/custodian entries' suggests you reach for this when raw holder registers are insufficient, but no explicit when-to-use, when-not-to-use, or alternative (e.g. get_shareholders) is given. An agent must infer the routing decision.

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