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

Annotations already declare destructiveHint=true and idempotentHint=true, so the safety profile is covered. The description adds real value by disclosing the partial-update behavior — only passed fields are sent and they overwrite current values — which is not conveyed by annotations. It does not cover auth requirements, but the extra mutation nuance justifies a 4.

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 clauses: action, method, endpoint. The most important operational caveat (overwrite semantics) is front-loaded and every sentence earns its place.

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?

For an update tool with full annotation coverage and a fully described schema, the description supplies the key missing context: it is a write and a path-based PUT. The only gap is a light lack of usage routing among dozens of siblings, but the essential calling information is present.

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 parameters. The description confirms that supplied fields are overwritten but adds no syntax, format, or constraint details beyond the schema. Baseline 3 is appropriate.

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 (change fields) and resource (one person), and the HTTP endpoint PUT /people/{id} pins it down. It is distinguishable from create_person, but it does not explicitly name a sibling alternative for partial updates.

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 description implies a single-record write and the 'only the fields you pass' note helps an agent understand update semantics, but it offers no explicit when-to-use context (e.g., when to use this vs update_company or vs creating a new person) and no prerequisite guidance.

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