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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds meaningful behavioral context beyond those annotations: the query protocol (DNS-over-HTTPS), the external scope ('no local context'), and the per-call cost. This is valuable for an agent deciding whether to invoke the tool.

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 a single dense sentence that front-loads the core purpose and record types, then adds key behavioral constraints. Every element earns its place with no filler or repetition.

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 simple one-parameter lookup tool, the description covers the domain target, the DNS record types returned, the transport, the read-only nature, and the paid cost. It does not detail response format or failure behavior, but no output schema exists and the tool is simple enough that this is a minor gap.

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 only one parameter, 'domain', and the schema already describes it fully with an example ('example.com'). Schema description coverage is 100%, so the description adds little beyond what the schema provides. Baseline 3 is appropriate.

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 clearly states the tool's purpose: DNS intelligence for a domain via DNS-over-HTTPS, and enumerates the exact record types returned (A, AAAA, MX, TXT, NS, CNAME). This distinguishes it from sibling tools like paid_cve_lookup or paid_gtin_lookup without ambiguity.

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 useful context ('via DNS-over-HTTPS', 'no local context', 'paid per call') but never explicitly states when to prefer this tool over alternatives or when not to use it. Sibling tools are unrelated, so no direct comparison is needed, but usage guidance remains implied rather than stated.

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