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

With no annotations, the description carries the full behavioral burden. It adds useful context by naming RDAP as the data source, listing returned fields, and disclosing a signed-wallet free-trial condition, but it does not explain cost after the trial, rate limits, or invalid-domain behavior.

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 definition is short and front-loaded, putting the core WHOIS lookup purpose first and the pricing/trial note second. There is minor redundancy in 'x402-whois: WHOIS', but no wasted sentences.

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 lookup tool with no output schema and no annotations, the description reasonably covers the data source and key return fields. However, it omits parameter guidance and error/payment details, which are important given two ambiguous optional parameters and no structured behavioral metadata.

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?

The schema has two parameters, host and domain, with 0% description coverage, and the description does not clarify which one to use or how they differ. It vaguely implies a domain input but leaves the optional host parameter and requiredness/format entirely undocumented.

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 verb and resource: 'WHOIS domain registration lookup via RDAP', and it names the key fields returned (registrar, dates, nameservers). It is clear what the tool does, but it does not distinguish itself from the many domain/registrar siblings such as x402-registrar-lookup or x402-domain-report.

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?

There is no explicit when-to-use guidance or routing to alternatives. A domain registration lookup is implied, but with many sibling domain tools available, the description should say when to choose this over x402-registrar-lookup, x402-domain-intel, or x402-domain-report.

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