DNS Lookup

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

Annotations already declare readOnlyHint=true, openWorldHint=true, idempotentHint=true, destructiveHint=false. Description adds valuable behavioral context: TXT records are returned raw with honest count, rate limits (30/hr free, 500/hr pro), and return structure. Does not contradict annotations; scores 4 for adding beyond 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?

Description is a single packed sentence but effectively front-loads purpose and key details. Every phrase adds value, no fluff. Could be slightly more structured, but overall concise.

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 simple input schema (1 param, fully described), presence of output schema, and annotations, the description provides sufficient context: explains return format, rate limits, and distinguishes from sibling. No gaps.

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 parameter 'domain' described clearly ('Root domain to query, without protocol or path'). The description does not add additional parameter meaning beyond what the schema provides, so 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?

Description is specific: 'Query all DNS record types (A, AAAA, MX, NS, TXT, CNAME, SOA) for a domain.' Lists clear use cases like mail routing, nameserver verification, SPF/DMARC checks, and explicitly distinguishes from sibling 'domain_report' for filtered TXT views.

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?

Explicitly states when to use this tool vs alternatives: 'Use for mail routing inspection, nameserver verification, or SPF/DMARC checks; for full overview use domain_report.' Also clarifies that TXT records are returned raw and 'total_txt_records' is honest, directing to domain_report for filtered view.

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