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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context that this surfaces 'real-time ownership changes between semi-annual filings,' but it omits practical traits such as pagination or coverage/rate limits, so it adds only moderate value beyond the annotations.

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 sentences, front-loaded with the core purpose and scope, with no real padding. The stat '9,704 classified SHINTR announcements' is slightly promotional but concisely conveys coverage, so the structure is efficient overall.

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 and annotations covering the safety profile, return values and reversibility need not be explained. The main gap is unresolved disambiguation from the many ownership-related siblings, which an agent needs in order to call this tool correctly rather than a neighbor.

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 baseline is 3. The description echoes the updatable dimensions (holder name, direction values) but adds no filtering syntax or defaults beyond what the schema already documents, so it does not meaningfully extend parameter understanding.

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 substantial holder notices (SPH) for an NZX company') and enriches it with the underlying data ('9,704 classified SHINTR announcements with holder name, type, percentage, direction'). However, it does not distinguish this tool from near-identical siblings like get_substantial_holders and get_substantial_holder_changes, leaving an agent unsure which to pick.

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?

It offers use-case context ('Use for M&A tracking, activist detection, institutional ownership changes') but these are scenario hints, not selection guidance. It never says when to prefer this over get_substantial_holders or get_substantial_holder_changes, so routing between the three is left to inference.

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