registrationUse when a domain has vanished from DNS and the person asks whether it expired or is on hold. Returns the registry's RDAP statuses and what each means for resolution, the dates and its nameservers; no contacts.
| Name | Required | Description | Default |
|---|---|---|---|
| domain | Yes | The domain or a hostname under it. Also as "name"; a URL is read as its host. |
Changes observed during successful MCP inspections.
Input schema / properties / domain / descriptionPrevious value: -"The registered domain or a hostname under it, e.g. example.com. Also accepted as \"name\"; a URL is reduced to its host."New value: +"The domain or a hostname under it. Also as \"name\"; a URL is read as its host."Input schema / properties / domain / descriptionPrevious value: -"The registered domain or a hostname under it, e.g. example.com"New value: +"The registered domain or a hostname under it, e.g. example.com. Also accepted as \"name\"; a URL is reduced to its host."Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly/idempotent/non-destructive/openWorld, so safety is covered. The description adds genuinely useful behavioral content the annotations can't: the response shape (statuses plus their resolution meaning, dates, nameservers) and a deliberate omission (no contacts), which matters since there is no output schema.
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, front-loaded with the usage trigger and followed by the return scope. No filler, no repetition of the title or annotations.
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?
With no output schema, the description carries the return-value burden and does so reasonably well (statuses, their resolution implications, dates, nameservers, absence of contacts). It does not mention behavior for unregistered/nonexistent domains, which is the one gap for a lookup tool.
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% and the single parameter's description already explains the domain/hostname/URL and "name" alias handling. The description adds no syntax or format detail beyond that, so the baseline 3 applies.
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 (returns the registry's RDAP statuses, dates and nameservers for a domain) and explicitly scopes what it does not return ("no contacts"). An agent can distinguish this registry-level RDAP lookup from the DNS-oriented siblings (dig, check_domain, trace) without opening a schema.
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?
Gives a concrete trigger: "when a domain has vanished from DNS and the person asks whether it expired or is on hold." That clearly separates it from live-resolution tools, though it never names a sibling alternative explicitly, so it stops short of the 5 bar.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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