dns_lookup

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It transparently states that the tool returns 'all available record types' and lists them, which is the key behavioral trait. It does not mention error handling, rate limits, or security requirements, but for a simple read-only lookup, this is reasonably complete.

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 that front-loads the action ('Query DNS records') before detailing record types and use cases. It is not overly verbose and avoids redundancy with the schema, earning a score above baseline.

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 simplicity (one parameter, no output schema) and the presence of siblings, the description adequately covers what an agent needs to know to call it correctly: what it does, what it returns, and typical use cases. It does not explicitly address edge cases like NXDOMAIN or empty responses, but these are minor for a lookup tool and the description is otherwise complete.

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 schema already covers the domain parameter fully (100% coverage) with format guidance and examples. The description adds no additional parameter semantics beyond 'domain name', so the baseline score of 3 is appropriate per the rubric.

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 uses a specific verb ('Query') and resource ('DNS records for a domain name'), and enumerates the exact record types returned (A, AAAA, MX, NS, etc.). This clearly distinguishes it from sibling tools like whois_lookup or ssl_check, which target different aspects of domain infrastructure.

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 use cases ('diagnosing DNS configuration, verifying mail settings, or auditing domain infrastructure'), which implicitly indicate when this tool is appropriate. However, it does not directly contrast with alternatives or state when not to use it, leaving some inference to the agent.

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