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

readOnlyHint=true already establishes the read-only profile, so the description only needs to add context — and it does, by disclosing the returned fields and the underlying Admin API route (GET /v1/admin/customers/{customerId}), which signals the admin scope/permissions involved. No error or not-found behavior is mentioned.

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 short sentences, zero filler, with the purpose front-loaded and the API detail placed after it as supporting context.

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?

There is no output schema, so the description's enumeration of returned fields (contact details, addresses, type) is the only signal about the response shape, and it is sufficient for a one-parameter getter. Minor gap: no not-found or auth-failure behavior for the admin endpoint.

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 the customer_id property already documents that it is a uuid sourced from twicecommerce_list_customers. The description's "by id" adds nothing beyond the schema, so 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?

States a specific verb and resource ("Get one customer by id") and enumerates the payload (contact details, addresses, type). The word "one" implicitly separates it from twicecommerce_list_customers, but no sibling is named explicitly.

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?

Usage is only implied: fetch a single record when you already have the id. There is no statement about when to prefer list_customers or get_customer_orders instead, and no prerequisites are called out.

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