DNS Lookup

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

Annotations already declare readOnlyHint=true, destructiveHint=false, idempotentHint=true, and openWorldHint=true, ensuring safety. The description adds valuable behavior: uses public resolvers (Cloudflare/Google/Quad9), returns a map of record types, and errors on malformed domains. No contradictions.

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 concise, front-loading the main purpose. It uses clear sections (Args, Returns, Examples, Errors) with no wasted words. Every sentence adds value.

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?

Given the tool's moderate complexity and rich annotations, the description fully covers input parameters, return format, error handling, examples, and references to siblings. An output schema exists, so return details are well-documented.

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%, baseline 3. The description adds context: domain example 'stripe.com', response_format defaults, and return structure (each record has type, host, value, priority?). This goes beyond the schema's minimal descriptions.

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 resolves all common DNS record types (A, AAAA, CNAME, MX, NS, TXT, SOA) for a domain, distinguishing it from sibling tools like ssl_certificate and whois_lookup. The verb 'resolve' combined with the resource 'DNS record types' makes the purpose specific and unambiguous.

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 provides explicit alternatives: 'Use ssl_certificate for TLS details, whois_lookup for registration data.' It also gives examples and notes error conditions. However, it doesn't comprehensively differentiate from all 18 sibling tools, especially other DNS-related ones like mx_lookup or dns_propagation, leaving some ambiguity.

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