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

Goes well beyond the readOnly/openWorld/idempotent annotations: discloses the resolution mechanism (DNS-over-HTTPS, RDAP), determinism and Ed25519 signing, the cost model and free-tier mechanics, and the exact scoring inputs. An agent knows the side effects, auth needs and cost before calling.

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?

Front-loaded with the payload and return contents, and dense with useful specifics. Minor waste in restating the pricing twice ('0.001 USDC via x402 on Base' and the bracketed '[x402: 0.001 USDC per call on Base]') and the trailing brand token.

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?

With no output schema, the description carries the return-value burden and does so by naming the record types, WHOIS fields, and the 0-100 score with letter grade components. Coverage is strong apart from error/partial-failure behavior.

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?

Only one parameter and schema coverage is 100%, so the schema already documents 'input' and the domain example. The description confirms the domain-shaped input but adds no format constraints or edge-case guidance beyond the schema's own example.

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?

States a specific verb+resource ('Full DNS + WHOIS/RDAP domain report in one call') and enumerates exactly what is resolved (A, AAAA, MX, TXT, NS, CNAME, SOA, DNSSEC) plus RDAP WHOIS fields and a hygiene score. No sibling tool covers this ground, so it is clearly distinguishable.

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 explains the invocation/payment path well (first 3 calls free via X-WALLET header, then paid), which is practical guidance, but it never says when to choose this over neighbors like registry_watch or who_gho_indicator_timeseries, nor any when-not conditions.

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