Diagnose a hostname

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

With readOnlyHint=true, the description adds valuable context about what the tool inspects (nameserver answers, public resolver views, certificate issuance). It clarifies the diagnostic nature without contradicting annotations.

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 concise sentences: the first explains the diagnostic output, the second gives usage advice. No filler; all information is relevant and front-loaded.

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 diagnostic tool with annotations covering safety, the description sufficiently explains what it does and when to use it. It could mention the output format, but that's not critical given the absence of an output schema.

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 100%, with the id parameter described as the hostname's id from list_hostnames. The tool description doesn't add additional parameter details beyond that, so baseline 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 clearly states the tool's function: it diagnoses why a hostname is or isn't working by checking nameservers, public resolvers, and certificate issuance. It differentiates from siblings like list_hostnames (listing), get_hostname (retrieving details), mint_hostname (creation), and repoint_hostname (modification).

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 advises using this tool before assuming a hostname is broken, and notes that a recently minted name may not have propagated yet. This provides clear context for when to use it, though it doesn't explicitly exclude alternatives.

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