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

The destructiveHint annotation already signals a write operation and the description is consistent with it, adding the parent-existence prerequisite. However, it says nothing about permissions/authentication, duplicate-email handling, or what happens to fields not supplied — meaningful gaps for a mutation tool whose only annotation is destructiveHint.

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 sentences, with the operation and its key decision (which parent identifier to pass) front-loaded. The trailing 'Atera: POST /api/v3/contacts' is low-value endpoint trivia but costs little.

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 create tool with no output schema, the description covers the essential decision (parent linkage) and the operation, but leaves the agent without guidance on the field-heavy area and on failure modes.

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 coverage is only 44%, and five parameters (phone, job_title, first_name, last_name, mobile_phone) are undocumented in both places. The description usefully resolves the customer_id-vs-customer_name choice, but adds little else beyond what the schema's own descriptions already say.

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 its scoping constraint ('under an existing customer'), which cleanly separates it from the read-oriented sibling atera_list_contacts. An agent can identify the operation without opening the schema.

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 clear prerequisite and the two acceptable ways to satisfy it ('give customer_id or customer_name'). It stops short of stating when not to use it (e.g., create the customer first, or use an update tool if the contact already exists).

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