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

Annotations supply only destructiveHint=true, so the description must carry the rest of the behavioral burden and does not: it is silent on duplicate-email handling, idempotency, whether the write is reversible, what permissions/auth are needed, and what the call returns. The endpoint string adds implementation trivia rather than behavioral context for the caller. (Note: 'create' vs destructiveHint=true is a mild tension but is a common conservative marking for POST writes, so it is not treated as a contradiction.)

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?

Two short clauses with the action and its core constraint front-loaded; nothing is padded or restated from the title. The trailing API endpoint reference is the only low-value token, but it is brief.

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 9-parameter mutation tool with no output schema and minimal annotations, the description leaves real gaps: it never states what the response contains (e.g. the new contact's identifier) even though no output schema exists to cover that, and it omits duplicate/error behavior. An agent can call it, but not confidently predict the outcome.

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 only 44% across 9 parameters, so the description should compensate more than it does. It does clarify the customer_id/customer_name alternative and that a customer association is expected, but the remaining fields (phone, mobile_phone, job_title, first_name, last_name, is_contact_person) receive no added meaning beyond the bare schema properties.

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 and resource ('Create a new end-user contact') plus the scoping constraint ('under an existing customer'), which is enough to separate it from list/read siblings. It does not, however, name or differentiate itself from any sibling explicitly (e.g. atera_list_contacts, atera_create_ticket), so it stops short of a 5.

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 parenthetical 'give customer_id or customer_name' is genuinely useful invocation guidance for the association requirement, but there is no when-to-use/when-not-to-use guidance, no statement of prerequisites (e.g. an existing customer must already exist), and no routing to alternatives. Usage is implied rather than framed.

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