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

Goes well beyond the annotations: it discloses side-effect scope ('sends nothing to the customer'), reversibility ('one edit in Kickserv undoes it'), the consequent no-confirmation policy, and a concrete auth requirement (Cotlet API key with app access). This is exactly the behavioral context annotations alone cannot convey.

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?

Front-loads the purpose and packs several distinct facts (return value, reversibility, dedup, auth) each of which earns its place. The opening 'New person or company contact...' sentence slightly overlaps with the following 'Creates a customer' clause, a minor redundancy.

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 mutation tool with no output schema, it covers the return value (customer_number), the reversibility/side-effect profile, the auth prerequisite, and the dedup workflow. Nothing an agent needs to invoke it correctly is missing.

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%, so the six parameters are already documented in the schema. The description alludes to service and billing addresses but adds no syntax, defaults, or format detail beyond what the schema provides, 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?

States a specific verb+resource ('Creates a customer and returns its customer_number') and clarifies the entity type (person or company contact with service/billing address). It also distinguishes itself from the read path by naming list_customers, so an agent can separate this create action from the lookup sibling.

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?

Gives a concrete usage rule: 'Search with list_customers before creating one, to avoid duplicates,' which tells the agent when to reach for the sibling first. It does not spell out explicit when-not conditions (e.g., when not to create), leaving that to inference.

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