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

Annotations already declare readOnly, idempotent, open-world, non-destructive, so the safety profile is covered. The description adds genuinely new behavioral context: the $0.005 per-call price, a free sample, and the fact that failures surface as errors/warnings/recommendations rather than raw exceptions. That is useful cost and output-shape disclosure beyond structured data.

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: purpose, pricing/sample, then return fields. Everything is front-loaded and nothing is padded. The return-field list is slightly machine-y but earns its place given there is no output 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?

For a single-parameter, read-only lookup with no output schema, the description is nearly complete: it covers purpose, cost, a sample call, and the returned fields. The only real gap is the absence of guidance on when this beats the overlapping domain_dns/security 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?

There is one parameter with 100% schema description coverage, so the schema already documents that 'domain' is a bare domain name with a 253-char cap. The description's sample value {'domain': 'example.com'} illustrates usage but adds no syntax or constraint detail beyond the schema. 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: it reports whether DNSSEC is signed and validates for a domain. That is clearly distinct from domain_dns, domain_tls, or domain_email_auth, though the description never explicitly contrasts with those siblings. The purpose is unambiguous on its own.

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?

Usage context is only implied by the topic (DNSSEC posture checks). There is no statement of when to prefer this over domain_dns, domain_security_score, or domain_email_auth, and no prerequisites or exclusions. An agent can infer the use case but gets no routing guidance.

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