dns_lookup

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

With no annotations, the description carries the behavioral disclosure burden. It states the tool queries authoritative DNS servers and returns records with TTL and query time, implying a read-only network operation. However, it omits details like rate limits, caching behavior, or error handling, leaving some transparency gaps.

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 well-structured with clear sections (Args, Returns), uses bullet points for clarity, and every sentence adds value. It is appropriately succinct for the complexity of the tool.

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 simple 2-parameter schema and no output schema or annotations, the description covers the tool's purpose, parameters, return format, and use cases comprehensively. Minor omissions like error handling or authentication requirements are acceptable for a read-only DNS lookup tool.

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?

The input schema has 0% description coverage, but the tool description extensively documents both parameters: domain with examples, record_types with supported types and detailed explanations (including defaults and example values). This adds significant meaning beyond the schema.

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's function: 'Look up DNS records for a domain across multiple record types.' It also lists specific use cases (email deliverability, domain ownership, CDN configuration, propagation status), distinguishing it from sibling tools like whois_lookup or ssl_check.

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 explicitly mentions when the tool is useful (diagnosing email deliverability, verifying domain ownership, etc.), providing practical context. However, it does not explicitly state when not to use it or mention alternative sibling tools, which would improve guidance.

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