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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds real behavioral context by disclosing that every authoritative nameserver is queried individually for reachability, recursion, TCP and consistency — implying multiple live network calls. It stops short of saying anything about runtime, rate limits, or how per-check failures are surfaced.

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?

One tightly packed sentence that front-loads the resource and then lists the audited areas, with no filler, hedging, or repeated annotation restatements. Every clause adds a distinct check to the reader's picture of the report.

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 must convey what comes back, and the enumerated checklist effectively describes the report's contents. What is missing is the shape of the result — whether each check returns pass/fail, values, or both — which matters for a multi-section diagnostic tool.

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?

There is a single parameter, 'domain', and schema description coverage is 100%, so the schema already carries the parameter semantics. The description only reinforces the scope ('for a domain') and adds no format guidance such as whether a subdomain, apex, or URL is acceptable.

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 resource (a domain's DNS) and enumerates exactly what is audited: root delegation, per-nameserver checks (reachability, recursion, TCP, consistency), SOA, MX with reverse DNS, SPF, DMARC, DKIM, DNSSEC. That enumeration makes clear this is the aggregate audit rather than a single-record lookup, though it never names a sibling to contrast with.

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 is only implied by the word 'Full' and the breadth of the checklist, which suggests this is the comprehensive option versus single-purpose checks. There is no explicit statement of when to pick this over dns_lookup, dkim_check, dnssec_check and the like, and no stated prerequisites (e.g. domain must be registered/delegated).

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