dns_lookup

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

Adds rate limits (100/hr free, 1000/hr Pro), discloses TXT record raw behavior and total_txt_records honesty, and notes return structure. Annotations already cover safety, but description enriches with operational details.

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?

Concise single paragraph with front-loaded purpose, followed by usage, behavior, rate limits, and return shape. 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 low complexity (1 param, good schema and annotations), the description fully covers purpose, usage, behavior, and output format. Agent can confidently select and invoke.

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?

Input schema covers the single parameter 'domain' with a clear description. No additional semantics added by description beyond the schema; baseline 3 justified.

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?

Clear verb+resource: 'Query all DNS record types for a domain'. Differentiates from sibling 'domain_report' by specifying that for a full overview, use the sibling.

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 use cases (mail routing, nameserver verification, SPF/DMARC) and when to use alternative (domain_report for filtered TXT view). Provides clear guidelines.

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