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

Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and network-touching behavior are covered. The description adds the scope of checks performed (delegation, NS count, SOA, reverse DNS) but says nothing about latency, failure modes, or per-check error reporting. With annotations carrying the safety profile, a 3 is appropriate.

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?

A single front-loaded sentence with zero filler; the scope list follows the main clause and every element earns its place.

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, and the one parameter plus read-only annotations are covered. The only gap is the absence of any signal about when to prefer this over the broader check_domain, which would help selection among eight siblings.

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% and the single 'domain' parameter is fully documented in the schema, including format constraints ('no scheme or path'). The description adds no parameter-level meaning, 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+resource ('Check DNSSEC validation and DNS health') and enumerates the concrete areas covered: delegation, nameserver count, SOA, and reverse DNS of mail servers. This clearly separates it from siblings like check_dkim or check_dmarc, though it does not distinguish it from the broader check_domain.

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?

There is no explicit when-to-use statement, no prerequisite (e.g. that the domain must be resolvable), and no routing guidance relative to check_domain, check_mx, or the other check_* siblings. The context is only inferable from the tool name and the list of checks.

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