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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true, so the safety profile is covered. The description adds the required OAuth scope, which annotations do not provide, but says nothing about pagination behavior or volume beyond what the schema states.

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 short fragments with zero filler, and the resource is front-loaded ahead of the scope and endpoint. It reads as terse documentation rather than a sentence, which is efficient but slightly clipped.

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?

The tool is simple and the schema fully covers paging, but with no output schema the description never indicates what fields a contact person record contains or that results are a paged list. That is a modest but real gap for an agent deciding whether this call answers its question.

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%, with limit, offset, and contact_id all documented inline including the next_offset paging convention. The description adds no parameter-level detail beyond the raw endpoint path, so 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?

The description names a specific resource (contact persons of one company contact) and pins it to an endpoint (GET /contacts/{contactId}/people), so the agent knows exactly what is returned. It does not explicitly differentiate itself from near-siblings such as smallinvoice_list_contact_addresses or smallinvoice_list_contact_groups, though the resource noun does most of that work.

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?

The scope requirement ('Needs the "contact" scope') gives a prerequisite, which is real guidance. However, there is no statement of when to prefer this over the sibling list tools for addresses, groups, or the parent contact itself, so selection still relies on inference from the name.

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