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

Annotations already declare readOnlyHint/openWorldHint/destructiveHint, so the safety profile is covered. The description adds genuine context beyond them: public resolvers (implying cached/non-authoritative results) and derived outputs like mail-server presence and SPF. It says nothing about rate limits, caching, or output shape.

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 opening 'DNS records of a domain. DNS records.' is pure repetition of the tool name and title and burns the most prominent position. The remainder is dense and useful, but the front-loading is wasted.

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 two-parameter read-only lookup with no output schema, the description tells the agent what it returns (record set plus mail-server/SPF signals) and how it resolves. Sufficient, though it could note result caching/authoritative differences.

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%, so both parameters are already documented, making 3 the baseline. The description's type list (A, AAAA, MX, NS, TXT, CNAME, SOA, CAA, SRV) is slightly richer than the schema's example for `types`, but adds no format guidance beyond what the schema gives.

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 verb+resource ("Look up DNS records of any domain") and enumerates the record types it returns, so the agent knows exactly what it gets. It does not differentiate itself from the very close sibling dns_propagation (or domain_whois), which is the main gap.

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?

"in one call" implies a batching benefit but there is no explicit when-to-use, no when-not-to-use, and no alternative named. With dns_propagation and domain_whois in the sibling list, the absence of any routing guidance is a real gap.

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