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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is handled structurally. The description adds useful behavior beyond that: it names the upstream service (Cloudflare DNS-over-HTTPS) and explains the all-in-one vs. single-type response behavior. It does not cover rate limits or error cases, but these are less critical given the read-only annotations.

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 two sentences with no filler. The first sentence packs the action, resource, record types, and optional mode; the second efficiently routes to alternatives.

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 two-parameter, read-only lookup tool, the description covers what the tool does, how to narrow it, which alternatives to use, and where the data comes from. The schema documents both parameters fully, and no output schema exists, but the explicit record-type list gives the agent enough context about expected results.

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%, with clear descriptions for both 'domain' and 'type'. The description adds meaning by listing the concrete DNS record types returned and confirming that omitting 'type' yields all six, which goes beyond the schema's generic wording.

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 opens with a specific action and resource: 'Returns DNS records for a domain via Cloudflare DNS-over-HTTPS' and explicitly enumerates the record types covered (A, AAAA, CNAME, MX, TXT, NS). It also differentiates itself from related siblings by naming whois_lookup and email_security for registration and email-security needs.

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 gives explicit routing guidance: 'For registration data use whois_lookup; for SPF/DMARC/DKIM analysis use email_security.' It also clarifies the two usage modes: return all six record types in one call or narrow to a single type via the 'type' parameter.

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