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

Beyond the annotations (readOnly, idempotent, non-destructive), the description discloses that no token is required, that all returned data is already public in DNS, and that the lookup fails once the name expires, including the exact timing of expiry. This is valuable behavioral context the annotations do not provide.

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 concise sentences, with the main purpose front-loaded and no filler. Each sentence adds relevant information: what it does, authentication implications, usage context, and failure behavior.

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 single-parameter, read-only tool with an output schema and comprehensive annotations, the description covers all the extra context an agent needs: purpose, usage, auth requirements, and expiry behavior. Nothing important is missing.

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?

The schema covers the only parameter, slug, with a clear description including the pattern, length, and the instruction to omit the prefix and zone. With 100% schema description coverage, the description does not need to add more, and it doesn't, so the baseline score of 3 is appropriate.

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 states a specific verb ('Look up') and resource ('temporary DNS name'), and specifies what it returns: the target and remaining lifetime. It is clearly distinguishable from sibling tools like create_dns_name, delete_dns_name, and update_dns_name.

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?

It provides clear use context: confirm a name exists and resolves as expected before handing it to someone else. It also notes that no token is needed. It does not explicitly contrast with alternatives, but the use case is specific enough for an agent to select it correctly.

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