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

Annotations already indicate this is a write operation (readOnlyHint=false). The description adds context by noting that a primary contact is created and that membership enrollment is optional and can be deferred, which is not fully encoded in the schema. It does not disclose side effects like duplicate handling, but for a create tool this is sufficient.

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 two sentences, front-loaded with the action, and contains no superfluous detail. Every word contributes to conveying the primary purpose and the key alternative. This is a model of conciseness.

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?

Given the output schema exists and the input schema is fully described, the description is adequate. It covers the core action and the enrollment deferral. It could mention when to use `create_contact` for standalone contacts, but for a create tool with rich schema, this is a minor 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 100%, so the baseline is 3. The description adds value by linking contact-related parameters (name, email, phone) to the notion of a 'primary contact', and clarifies that enrollment is optional. This provides interpretive guidance beyond the standalone field descriptions.

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 states the tool creates a CRM account/customer, with the specific verb 'Create' and the resource 'account/customer'. It also mentions the primary contact feature, distinguishing it from generic contact creation. This is unambiguous and action-oriented.

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 description explicitly directs the user to use `enrol_membership` when the account already exists, providing a clear when-not to use this tool for membership enrollment. This gives an actionable alternative, satisfying the 'explicit when/when-not/alternatives' criterion.

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