Whoisfreaks

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Domain availability check

domainAvailability

Read-onlyIdempotent

Check whether a domain name is available to register using DNS and WHOIS data, and optionally get alternative names with other extensions marked available or not.

Instructions

Check whether a domain name is available to register, using both DNS and WHOIS data. Use this before suggesting or buying a domain name. Set suggestions=true to also get alternative names with other extensions, each marked available or not; count sets how many (5-100). To check a list of names, or one name across many extensions, use bulkDomainAvailability. For details about who owns a registered domain use liveWhoisLookup. Costs 1 credit, plus 1 credit per 5 suggestions. Returns the availability (AVAILABLE or UNAVAILABLE), or with suggestions a list of names each with domainAvailability true or false. Availability can change at any moment, and this check does not reserve the domain. Behavior: read-only. Makes one request to the WhoisFreaks API using your WhoisFreaks API key (the WHOISFREAKS_API_KEY environment variable, or on the hosted server the key sent with the request) and uses that account's API credits; nothing is created or changed. If the call fails, the result is a short message instead of data, for example: key invalid, or plan or credits used up (HTTP 401), domain extension not supported (HTTP 403), no data found (HTTP 404), or rate limit reached (HTTP 429).

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "domain": "<domain>"
    },
    "name": "domainAvailability"
  }
}

Input Schema

Name	Required	Description
`count`	No	Number of suggestions to return when suggestions=true, 5 to 100. Default: 5
`domain`	Yes	Domain name to check availability for. Example: whoisfreaks.com
`format`	No	Response format. Default: json
`suggestions`	No	If true, also return alternative domain names with other extensions and whether each is available. Default: false

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedv2.1.0Nov 13, 2026

changedInput schema / properties / count / description

Previous value: -"Number of suggestions to return when suggestions=true. Range: 1–100. Default: 5"New value: +"Number of suggestions to return when suggestions=true, 5 to 100. Default: 5"

addedInput schema / properties / count / maximum
```
Added value: +100
```
addedInput schema / properties / count / minimum
```
Added value: +5
```

changedInput schema / properties / suggestions / description

Previous value: -"If true, also return alternative domain name suggestions. Default: false"New value: +"If true, also return alternative domain names with other extensions and whether each is available. Default: false"

First observedv1.0.2Nov 11, 2026

TDQS

A4.8/5.0

Behavior5/5

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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, yet the description adds real context: per-call credit cost plus 1 credit per 5 suggestions, the required WHOISFREAKS_API_KEY and whose credits are consumed, the volatility caveat that availability can change and is not reserved, and concrete HTTP 401/403/404/429 failure outcomes. That goes well beyond the annotation bar and is exactly what an agent needs before spending a user's credits.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Purpose and routing come first, followed by cost and return behavior, which is good front-loading. The paragraph enumerating HTTP status codes is the longest block and slightly heavy, but each line is genuinely diagnostic rather than filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

There is no output schema, yet the description documents the return shape (AVAILABLE/UNAVAILABLE, or a suggestion list with per-name booleans) and what a failure looks like instead of data. Cost, auth, and failure modes are all covered, so nothing an agent needs to invoke it correctly is missing.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

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 earns an extra point by tying 'count' to billing ('1 credit per 5 suggestions') and by explaining that each suggestion is individually marked with domainAvailability true or false, which the schema alone does not convey. 'format' is left to the schema, which is acceptable given full coverage.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description opens with a specific verb and resource ('Check whether a domain name is available to register') and immediately scopes the data sources used (DNS and WHOIS). It explicitly routes apart from bulkDomainAvailability and liveWhoisLookup, so an agent can distinguish it from siblings without opening any schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines5/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

It states the use case ('Use this before suggesting or buying a domain name'), the condition for the suggestions flag and its range, and names two alternatives with the conditions that select them (lists or many extensions → bulkDomainAvailability; ownership details → liveWhoisLookup). No inference is required.

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