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

Annotations already declare destructiveHint=true, and the description adds a genuinely useful behavioral fact: only provided fields are changed (patch-like semantics). However, it omits the important nuance visible in the schema that array fields like tags, emails and phone_numbers are wholesale replaced rather than merged, and it gives no auth/permission or error context for a destructive write.

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, zero filler, with the core behavior front-loaded. The trailing 'Copper REST: PUT /people/{id}' line is developer-oriented trivia that adds little to tool selection, so not quite a 5.

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 9-parameter destructive update with no output schema and no annotations beyond destructiveHint, the description covers the essentials but leaves gaps: no mention of the array-replacement behavior, no confirmation of update-vs-replace at the top level beyond one clause, and no error/failure context.

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% across all 9 parameters, so the schema already carries the field-level meaning. The description only adds the top-level partial-update rule and does not extend per-parameter semantics, so the 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?

Clear specific verb+resource ('Update fields on an existing person'), and the partial-update clause pins down the semantics of the operation. It implicitly distinguishes itself from copper_create_person, but never names the sibling or explicitly contrasts create vs update boundaries.

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 word 'existing' implies the entity must already exist, which is the only usage cue. There is no guidance on prerequisites (e.g. resolving the id via copper_get_person) or on when to prefer a more specific sibling tool.

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