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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds real value beyond them: the dns:read auth scope requirement and the domain-eligibility limitation. It doesn't mention pagination or rate limits, so it falls short of a 5.

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?

Three tightly packed sentences, front-loaded with the operation and scope, then return contents, then preconditions. Every sentence carries distinct information with no filler.

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?

With no output schema, the description usefully previews return content (provider id for update/delete, mailCritical flag with examples) and states both the auth scope and the domain-eligibility constraint. An agent has everything needed to decide and call correctly.

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?

Only one parameter, and schema description coverage is 100% ('Domain name, e.g. "yourdomain.com". Must be on the account.'). The description adds nothing about the domain parameter beyond what the schema already states, so the baseline 3 applies.

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 (list) and resource (live DNS zone records of a domain) with clear scope ('live DNS zone records of a domain on the account'). The resource is unmistakably distinct from siblings like create_dns_record, update_dns_record, and list_domains.

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 concrete preconditions: 'Requires the dns:read scope' and 'Only works for domains with live DNS editing (Faivelo-registered or a connected registrar API key).' It stops short of naming alternatives or when-not-to-use cases, but the constraints clearly frame when the call will succeed.

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