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

Annotations already declare destructiveHint=true, and the description earns its keep by explaining exactly what is destructive: only supplied fields change, while list-valued fields (emails, phones, groups, companies) REPLACE rather than append. That is the key non-obvious behavior behind the hint, though it stops short of covering permissions or response behavior.

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 sentences, front-loaded with the core action and the most important caveat (replacement semantics), with no filler or repetition.

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 a 15-parameter mutation tool with no output schema, the description covers the partial-update contract and the destructive replacement rule, which is what an agent most needs. Auth/error expectations are the only real omissions.

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 all 15 parameters are already documented in the schema, including per-field 'Replace the ...' wording. The description only generalizes that rule for the list fields, adding little beyond what is already structured.

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 + resource ('Update fields on an existing person') and immediately scopes it as a partial update, which cleanly distinguishes it from the create_person sibling. The REST mapping (PATCH /v1/people/{id}) removes any ambiguity about the operation.

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 the tool applies to already-existing people and clarifies partial-update semantics, but it never names an alternative (e.g., use folk_create_person for new records) or states when-not to use it. Usage is inferable rather than explicitly guided.

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