DNS Lookup

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

Annotations provide readOnlyHint=true, openWorldHint=true, idempotentHint=true, and destructiveHint=false — a strong safety profile. The description adds the critical cost disclosure ($0.02 USDC on Base), which is behavioral transparency beyond annotations. It also conveys the payment-gated nature of the call. The payment flow detail is actually in the schema parameter description rather than the main description, which slightly limits credit.

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, information-dense sentence: states the action, enumerates supported record types, scopes to any domain, and discloses cost. Every word earns its place. The payment mechanics are appropriately delegated to the parameter schema rather than bloating the description.

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?

The tool is simple (2 params, 1 required, no enums, no nesting) with a full output schema, so the description doesn't need to explain return values. The cost disclosure and record-type enumeration make it reasonably complete for agent invocation. The only gap is that no explicit note about rate limits or auth flow prerequisites beyond _payment appears in the main description, though the _payment param description covers the flow.

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% (both parameters are described in the schema). The _payment parameter has rich semantics explaining the signing process, local key handling, and the two-step retry pattern. The description adds the pragmatic cost dimension. With complete schema coverage and strong parameter descriptions, this earns a high score.

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?

Description states a clear verb+resource ('Look up DNS records') and lists specific record types (A, AAAA, MX, NS, TXT, SOA) for a domain. It's distinct from sibling tools which cover QR, images, documents, email, OCR, etc. However, it doesn't explicitly name any sibling as an alternative for related lookups, though none of the siblings are network lookup tools, so differentiation is inherently clear.

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 implies usage (looking up DNS records for any domain) and provides the cost context. It mentions the payment requirement in the schema parameter description, explaining the two-step flow (call without _payment first, then retry). No exclusionary guidance against alternatives exists, but none of the siblings do DNS lookups, so this is acceptable.

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