whoisRetrieve WHOIS registration data for a domain, including owner, registrar, and expiration details, to verify domain ownership or investigate domain history.
Legacy alias for domain.whois (GET /v1/whois). Prefer domain.whois.
| Name | Required | Description | Default |
|---|---|---|---|
| domain | Yes | Domain name. Example: 'example.com'. |
Changes observed during successful MCP inspections.
v0.3.4Input schema / properties / domain / descriptionPrevious value: -"Domain name (e.g. example.com)"New value: +"Domain name. Example: 'example.com'."v0.3.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and non-destructive behavior, so the safety profile is covered. The description adds the useful context that this is a legacy alias and exposes the exact endpoint, but does not disclose additional behavioral details such as response format or rate limits. With strong annotation coverage, this is adequate.
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 sentences, no filler, with the legacy alias status and preferred alternative front-loaded. Every sentence earns its place.
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 one-parameter, read-only legacy alias with rich annotations and a fully covered schema, the description is nearly complete. It does not describe return values, but since the tool is explicitly an alias for domain.whois, an agent can reasonably infer behavior from the canonical sibling.
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 covers 100% of the single parameter, including a description and example ('example.com'), so the schema already carries the semantic weight. The description adds no parameter-level information beyond what the schema provides. 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 clearly identifies the tool as a legacy alias for domain.whois and gives the endpoint (GET /v1/whois), which conveys its function indirectly. It distinguishes itself from the canonical sibling by explicitly naming domain.whois, though it never directly states 'performs WHOIS lookup'.
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 instruction 'Prefer domain.whois' gives explicit routing guidance toward the preferred sibling instead of this legacy alias. It does not spell out all conditions for when the alias should be used, but the legacy/alias framing makes the context clear.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.