Create customer

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

Annotations already declare readOnlyHint=false, and the description reinforces this with 'Write operation'. It adds meaningful context by noting that the tool 'stores personal data', signaling persistence and privacy implications. There is no contradiction with annotations, but other side effects are not disclosed.

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 description is a single, tight sentence with the operation type and resource front-loaded. There is no filler or redundancy. However, the brevity comes at the cost of omitting parameter and behavioral details.

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?

With five parameters, no parameter descriptions, no output schema, and minimal annotations, the description is not sufficient for an agent to invoke the tool correctly. It leaves out return value, duplicate handling, idempotency behavior, and what happens after a successful creation.

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 0%, and the description names none of the five parameters. It does not explain the required email, the purpose of idempotencyKey, or how phone and name fields relate to the stored personal data. The description fails to compensate for the schema's complete lack of parameter documentation.

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 uses a specific verb and resource: 'create a customer record in ZEN', and states its purpose, 'for future payment flows'. This clearly identifies the tool's domain and helps distinguish it from siblings like create_payment_link, which create a different resource.

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 phrase 'for future payment flows' implies this is a setup step before payment operations, providing some usage context. However, it does not explicitly state when to use this tool versus alternatives, nor does it mention prerequisites such as whether a customer email must be unique.

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