Create a customer

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

Beyond the generic mutation and safety annotations, it discloses that every field may be omitted and that a duplicate email produces the concrete `409 customer_exists` failure. It does not explain other side effects or success behavior, but the uniqueness rule is actionable operational context.

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?

The definition is short and front-loads the operation, rationale, optionality, and conflict behavior without unnecessary detail. Repeating 'Create a customer' at the start of both paragraphs is mildly redundant.

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 relatively simple six-field creation operation, the purpose, optionality, duplicate-email behavior, and schema-level idempotency guidance are sufficient for a correct basic invocation. Remaining gaps include the unexplained phrase 'in this mode' and the absence of an explicit existing-customer workflow.

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?

The description adds meaningful semantics for email through its mode-scoped uniqueness constraint and states the global optionality of all fields. With only 33% schema description coverage, it does not fully compensate for undocumented fields such as name, phone, and metadata.

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?

The description clearly identifies the operation as creating a customer and explains the record's role in issuing virtual accounts, invoices, and subscriptions while grouping payments. It does not explicitly distinguish the operation from siblings such as update_customer or list_customers.

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 downstream uses provide clear context for when a customer record is useful. However, there is no explicit when-not guidance or instruction to find and reuse an existing customer rather than create another one.

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