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

Annotations already flag this as a mutating, non-idempotent, destructive, open-world call, so the safety bar is partly covered. The description adds real value by disclosing the local WordPress authentication path and that REST API keys are unnecessary, but it says nothing about failure modes (duplicate email), what is created/returned, or why the call is destructive.

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?

Two tight sentences, with the action front-loaded and the auth caveat second. The reference to the upstream `create_customer` method is somewhat internal but conveys behavioral parity, so little is wasted.

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?

This is a destructive, non-idempotent write whose main parameter is a free-form nested object with no documented fields; the description gives no help on what customerData should contain or what happens on conflict. The authentication note is welcome but insufficient for a mutation tool of this shape.

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 coverage is 100%, and site_id's schema text already explains using the list_sites id rather than a URL or post ID. The description adds no meaning beyond the schema for customerData, which is an empty nested object with additionalProperties=true.

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 and resource: 'Creates a WooCommerce customer.' Clear enough that an agent can distinguish it from wc_update_customer and wc_get_customer from the name plus this sentence, though the description itself never names those siblings.

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?

No guidance on when to create a customer versus updating one, no prerequisites, no mention of duplicate-email behavior or required fields. The only contextual note is about authentication ('no WooCommerce REST API keys are required'), which is useful but is not usage guidance.

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