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

Annotations already declare the safe-create profile (readOnlyHint=false, destructiveHint=false, openWorldHint=false), so the bar is lower, and the description still adds a non-obvious, irreversible consequence: duplicates are unmergeable. It also stresses email fidelity to the merchant's own form. It stops short of auth/permission or rate-limit details.

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-loaded with the action, followed by the sequencing rule and the data-integrity rule in tight, waste-free prose. Every sentence carries a distinct warning or instruction.

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 7-param, nested-object mutation tool with no output schema, the description covers the critical risks (duplicates, required email, not fabricating data) but says nothing about partial-address handling or what the call returns on success. Since no output schema exists, the missing return detail is a minor, acceptable gap.

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 71%, so the schema carries most parameter meaning. The description nonetheless reinforces the one required field ('Email is required, exactly as in the cabinet's own customer form') and adds data-quality semantics for phone/address. It does not clarify the billing/shipping override relationship beyond what the schema states.

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 first sentence gives a precise verb+resource combination ('Create a customer') that is unambiguous. It also references the sibling get_customers as a prerequisite, which helps positioning, though it does not explicitly contrast with hub_update_customer or hub_import_customers. Clear but not maximally differentiated from all 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?

It states an explicit precondition ('Call get_customers with the email or name FIRST'), explains the cost of skipping it (duplicate splits order history, no merge exists), and adds an escalation rule ('Ask the merchant for anything you do not know instead of inventing it'). This is exactly the when/when-not guidance the dimension rewards.

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