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

Annotations already declare readOnlyHint, openWorldHint and destructiveHint=false, so the safety profile is covered. The description nonetheless adds a genuinely useful behavioral trait the annotations cannot: the measurement vantage point is a Korean network, with named Korean ISP and public resolvers, which affects what results mean. It omits timing/polling behavior and expected latency.

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 sentences, front-loaded with the core action and the resolver set before the use case. The parenthetical resolver list (KT, SK Broadband, LG U+, Cloudflare, Google, Quad9, OpenDNS) is long but earns its place by defining measurement scope.

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, so the description carries the burden of explaining what comes back; it never says whether the result is a match/mismatch verdict or a per-resolver answer list. It is adequate for selection but leaves the agent guessing about the return shape and about how long propagation checks may take.

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 50%: name is documented in the schema, while type has only an enum and no description. The description compensates partially by showing a record-name example (_acme-challenge.example.com) and highlighting TXT/CNAME, but adds no guidance on why a given type matters or on record-name formatting rules. Baseline 3 for a half-documented schema.

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 gives a specific verb (compare) and resource (answers for one DNS record) plus an explicit scope: authoritative nameservers, Korean ISPs, and public resolvers. That scope cleanly separates it from the generic-sounding sibling check_dns, so an agent can pick it without opening schemas.

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?

It states a concrete use case: confirming a TXT/CNAME for certificate domain validation (e.g. _acme-challenge) has propagated. That is clear when-to-use guidance, but it names no alternative (e.g. check_dns, check_certificate) and gives no when-NOT-to-use condition.

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