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

Annotations already declare readOnly, idempotent, and openWorld, so the safety profile is covered. The description adds real behavioral context beyond them: the DoH transport, which resolvers are used (Cloudflare or Google), that SPF/DMARC are parsed as a side effect, and that private names are actively refused.

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 short sentences, front-loaded with the core action and record types, with constraints trailing. Every sentence carries information; no padding or restatement of the name.

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 an output schema present, return values need not be explained, and annotations cover the safety profile. The description supplies the transport, resolver, refusal constraint, and SPF/DMARC behavior, which is enough for an agent to call the tool correctly.

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 50% – 'types' and 'resolver' have enums/defaults that self-document, while 'mail' and 'name' are described in the schema. The description restates the record types and resolver options and hints that SPF/DMARC parsing is tied to mail handling, but it does not fully compensate for the undocumented half.

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 (Query) and resource (DNS records), enumerates the exact record types, and names the transport (DNS-over-HTTPS) and hostname scope (public). It is clearly distinguishable from siblings like check_ssl or check_http_headers, though it does not explicitly contrast itself with any of them.

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 is implied rather than stated: an agent infers it should call this when it needs DNS records for a hostname. The description gives one useful exclusion ('Private names are refused') but names no alternatives or explicit when-not conditions, so guidance is only adequate.

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