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

With no annotations, the description carries the full burden and does well: it declares 'Read-only' and, importantly, bounds its own claim by stating the DNSSEC signal is 'DNSKEY presence + Authenticated-Data flag — not a full chain validation'. That prevents an agent from over-trusting the result. It stops short of mentioning rate limits, auth, or query behavior.

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?

One tightly packed sentence with the primary resource (CAA) front-loaded, followed by the secondary signal and its caveat. No filler; every clause carries information.

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?

There is no output schema and no annotations, so the description must convey return content, and it does — it names the two result categories and their interpretation. It is nearly complete, missing only error/no-record behavior and pagination or output-shape detail.

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 description coverage is 100% for the single 'domain' parameter, so the schema already documents the field and its example. The description adds no extra syntax, format, or edge-case detail (e.g. subdomain handling) beyond what is already structured, so the baseline 3 applies.

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?

Specific verb+resource: reports a domain's CAA records, and explicitly parenthesizes what CAA means ('which CAs may issue its certificates'). It also names the second output (DNSSEC signal) precisely, so an agent can distinguish it from generic dns_lookup.

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?

Usage is implied (checking which CAs are authorized to issue certs), but there is no explicit when-to-use guidance, no prerequisites, and no routing to or away from siblings such as dns_lookup, cert_transparency, or cert_revocation.

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