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

No annotations are provided, so the description carries the full burden. It discloses that authentication is required and imposes phone/country format constraints, but it does not mention what happens on success, whether duplicates are allowed, or what the return value contains. These are notable gaps for a mutation tool.

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 compact and front-loaded: purpose, authentication, then required/optional fields. Every sentence earns its place, and the field list is easy to scan despite the large parameter count.

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?

The input requirements are well covered, but the description does not state the response shape or return value, and there is no output schema to fill that gap. It also leaves the sessionKey authentication flow implicit, though the schema partially covers that.

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 8%, and the description compensates by enumerating all required and optional contact fields. It adds real meaning by specifying E.164 for phone and ISO 3166-1 alpha-2 for country. It does omit sessionKey, but the schema itself provides a thorough description for that parameter.

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 uses a specific verb-resource pair, 'Create a new contact', and states the purpose, 'for use with domain registrations.' This clearly distinguishes it from sibling tools such as updateContact, deleteContact, getContact, and listContacts.

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 gives clear context: create a contact for domain registrations, and it states the required authentication precondition. It does not explicitly explain when not to use it or contrast it with updateContact for existing contacts, but the intended use case is clear.

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