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

Annotations already establish that this is a write/destructive tool with idempotent behavior, so the description does not need to restate that. It adds a small amount of context by specifying 'existing people' and pointing to the write-tools skill, but it does not disclose what happens to omitted fields, null values, or failed updates.

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?

The description is two sentences with no wasted words: the first sentence states the operation and the second gives a concrete prerequisite. It is well-structured and front-loaded with the core purpose.

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 schema provides types and constraints, and annotations supply the safety profile, but the description leaves important semantics unstated, such as whether nested connections are replaced or merged and how null values behave. The pointer to the write-tools skill helps, but the description is not self-sufficient for correct invocation.

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 0%, and the description does not elaborate on the people array, the required personId, or the meaning of fields like connections and primaryEmail. The phrase 'fields' is generic and adds no parameter-level semantics.

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 opens with a specific action ('Update fields') and target resource ('existing people'), and the plural phrasing ('one or more') signals batch capability. This is enough to distinguish it from sibling tools like create_companies, merge_people, and add_people_to_company.

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 only explicit usage instruction is the prerequisite to read the write-tools skill before the first call. There is no guidance on when to choose this tool versus alternatives such as merge_people or update_companies, so the intended use case must be inferred from the name and opening sentence.

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