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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds genuinely useful behavior beyond that: a per-call cost of $0.02 USDC with two payment mechanisms (x402 or credits), which an agent must know before invoking. It omits any note on rate limits or result caching, keeping it short of a 5.

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 zero padding; the scope is front-loaded and the cost caveat follows. 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?

For a simple one-parameter read tool with no output schema, the description tells the agent what data categories come back and what the call costs. It is nearly complete; the only gap is domain-input format expectations.

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% ("Domain name"), so the schema fully documents it. The description adds no format detail (e.g., whether a bare domain or URL is accepted), which is the baseline-3 case when the schema carries the load.

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 (domain report) and enumerates exactly what it aggregates: registration, DNS, email provider, SPF/DMARC, hosting. That implicitly distinguishes it from the narrower siblings lookup_dns/lookup_whois, but it never names those alternatives, so differentiation is left to inference.

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?

"One-call domain report" implies this is the consolidated alternative to the single-purpose lookup tools, and the pricing note hints at a cost consideration, but there is no explicit when-to-use vs when-to-prefer lookup_dns or lookup_whois guidance.

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