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

There are no annotations, so the description carries the full burden. It discloses the method ('via WHOIS'), the checked record types, and the outcome ('flags common misconfigurations'), which is sufficient behavioral transparency for a read-only diagnostic tool. It does not describe edge cases like invalid domains, but the core behavior is not hidden.

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 a single front-loaded sentence that lists the exact checks and ends with the value-add ('flags common misconfigurations'). There is no redundant or filler wording.

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 one well-documented parameter, no annotations, and no output schema, the description is almost complete: an agent knows exactly what is checked and that misconfigurations are flagged. It does not detail return shape or failure modes, which would strengthen it, but the core information needed to invoke the tool is present.

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 input schema already documents the only parameter well: 'Bare domain to check, e.g. example.com (no scheme/path)' with 100% coverage. The description adds no additional parameter-specific meaning, so the baseline score of 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?

The description names a specific verb ('Check'), resource ('a domain'), and the exact scope: registration expiry via WHOIS plus DNS records such as nameservers, A/AAAA, MX, SPF, and DMARC. This distinguishes it from sibling tools like domain_availability_check or dns_propagation_check because it clearly covers health-and-misconfiguration checking rather than availability or propagation alone.

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 makes the use case clear: use it to check domain registration expiry, DNS record setup, and common misconfigurations. It does not explicitly name alternative tools or state when not to use it, but the scope is specific enough for an agent to select it appropriately.

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