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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds valuable behavioral context beyond annotations: paid plans, $4.99 USDC per search via x402 on Base or Solana without an API key, and charging only when records are found. It does not cover rate limits or output format, but the payment behavior is well disclosed.

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 compact and front-loads the core purpose before pricing details. The first sentence is slightly awkward but carries essential scope information, and the remaining sentences efficiently cover payment behavior without waste.

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 single-parameter tool with annotations and no output schema, the description covers purpose and payment well. However, it leaves the meaning of 'records' and 'the data seen for each' vague and does not help the agent distinguish this from several domain-related siblings, which is a real gap in a crowded toolset.

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 100%, so the baseline is 3. The description adds meaning beyond the schema's 'Domain, e.g. example.com' by clarifying that the domain is used to find accounts at 'every address @domain'. This helps the agent understand the parameter as an email domain scope rather than a generic domain lookup.

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 the resource and scope clearly: 'Records found for accounts under a domain (every address @domain), with the data seen for each.' It communicates that this is a domain-level OSINT retrieval tool returning per-account records. It does not differentiate from closely related siblings such as domain_emails, domain_ips, or domain_whois, which limits it to a 4.

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 guidance on when to use this tool versus alternatives. It mentions paid plans and x402 payment, but does not say when to choose this over domain_emails or osint-email, nor does it describe prerequisites like authentication with an API key.

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