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

Beyond the annotations, the description discloses the payment model in concrete detail: $0.005 USDC on Base per call via x402, unpaid calls return PaymentRequired, and compatible x402 MCP clients pay automatically. It also enumerates the behavioral outputs, including risk flags such as newly_registered_lt_30d, which materially improves transparency for an agent deciding whether and how to invoke it.

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 description is front-loaded with the main value proposition, then compactly lists coverage areas and payment behavior. Every clause earns its place, and the cost/payment caveat is placed at the end without obscuring the core purpose.

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 complex multi-check aggregate tool with no output schema, the description is largely complete: it enumerates the report sections and risk flags and explains the x402 payment flow. It does not describe response structure, error behavior beyond payment, or data freshness, so it falls just short of fully complete.

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 the schema already fully documents the single required domain parameter with an example. The description does not add format, normalization, or validation details beyond what the schema provides, so baseline 3 is appropriate.

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 states a specific aggregate operation—a one-call domain due diligence report—and enumerates the exact coverage areas: RDAP, DNS, email setup, HTTPS security headers, and risk flags. It clearly distinguishes itself as an aggregate report rather than a single-purpose lookup, though it does not explicitly name the sibling tools it replaces.

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?

The phrase 'one-call domain due diligence' and the coverage list make the intended use clear: gathering a broad domain risk snapshot in one call rather than making separate DNS, WHOIS, email, or URL checks. It does not spell out when-not-to-use conditions or explicitly route agents to dns_lookup, domain_whois, or email_domain_check for narrower needs.

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