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

With no annotations, the description carries the full burden, and it does disclose the underlying source (Cloudflare/Google DNS-over-HTTPS), which implies a public, unauthenticated read. However, it says nothing about behavior for nonexistent domains (NXDOMAIN), rate limits, or what happens when the optional type filter is omitted, all of which matter for an unannotated tool.

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?

Two dense sentences with no filler: return payload first, use cases second. The most discriminating information (the record-type coverage) is front-loaded.

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?

Only two parameters and an output schema exists, so return-value explanation is rightly omitted. Purpose, source, and use cases are all covered; the one missing piece is the semantics/default of `types`, which leaves a small but real hole for an otherwise simple 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?

Schema coverage is 0%, so the description must compensate. It does partially: the enumerated record-type list effectively tells the agent what values `types` accepts, and `domain` is self-evident. But it never states the accepted format (comma-separated string vs. single type), nor the default behavior when `types` is null — a real gap for the one non-obvious parameter.

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 names a specific resource and enumerates exactly what it returns (A, AAAA, MX, TXT, NS, CNAME, SOA, CAA, plus SPF and DNSSEC status), which cleanly separates it from adjacent siblings like domain_whois, ssl_certificate and email_security. It is a noun phrase rather than an explicit verb+resource, and it never directly names a sibling it is not, so it falls just short of a 5.

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?

"Use to check where a domain points, its mail servers, verification TXT records or why email or a website is failing" gives concrete when-to-use scenarios. There is no explicit when-not guidance and no named alternative (e.g., for WHOIS registration data vs. DNS records), so it is clear context without exclusions.

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