Domain WHOIS, DNS and email audit

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

Annotations already declare this a read-only, idempotent, open-world, non-destructive operation, so the safety profile is covered. The description adds that the lookup is split into DNS and email-security halves, but discloses nothing about rate limits, failures on non-existent domains, or external source variability that an agent would find useful.

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 tight sentences with the payload list front-loaded and the toggles noted last. Nothing is padded, though the final toggle sentence is largely redundant with the schema.

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?

An output schema exists, so return values need no explanation here, and the description covers scope, toggles, and intended use. A note on behavior for non-existent or malformed domains would complete it, but it is otherwise sufficient for correct invocation.

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 100%, so all three parameters are fully documented in the schema, including defaults and the URL-to-host normalization. The description's note that include_dns/include_security toggle the two halves restates what the schema already conveys, 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 (lookup) and resource (domain) and enumerates the concrete payloads: WHOIS, DNS records, and an SPF/DMARC email audit. This distinguishes it from the sibling company-lookup tools, which fetch entity data rather than domain infrastructure.

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?

"Use it to profile a company's web estate or check its email posture" gives clear context for when to reach for this tool. It stops short of naming an alternative or exclusion (e.g., when to prefer find_company_by_domain or enrich_company instead), so it is not a full when/when-not statement.

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