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

With no annotations provided, the description carries the burden of behavioral disclosure. It states that responses are 'signed with the time', indicating a timestamp, and explicitly notes that DNSSEC is not validated and the response says so. This discloses a limitation and a behavioral trait, which is helpful for an agent deciding whether the answer is sufficient.

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 two sentences with no wasted words. The primary action is front-loaded, followed by a concise note on reliability and a limitation. It is tightly written and easy to parse.

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?

For a simple two-parameter lookup tool with no output schema, the description provides essential context: what it does, the record types, and a reliability caveat. It doesn't describe the return format, but that is likely self-evident for a DNS lookup. The description is sufficiently complete for an agent to call the tool correctly.

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%, so the schema already documents both parameters well. The description adds minimal extra meaning beyond what the schema says: it lists the record types again, but doesn't provide additional syntax or format details. Since the schema covers the parameters, a baseline score of 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?

The description clearly states the action (look up) and the resource (DNS records for a public hostname) and enumerates the exact record types (A, AAAA, CNAME, TXT, MX, NS). It distinguishes the tool from siblings by specifying its scope and reliability, making it unambiguous even among many sibling tools.

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 implies when to use the tool: when you need authoritative, checked DNS records rather than model-invented data. It doesn't explicitly mention alternatives, but it sets a clear expectation of accuracy, which guides an agent to prefer it for factual lookups. It lacks explicit exclusions but the context is sufficient.

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