MCP server documentation

Just Domain turns any MCP-aware assistant into a domain-naming partner. Ask the assistant to find a domain, and it calls search_domains against our registrar backend to return live availability and price for the TLDs you care about. The assistant suggests candidates; the user opens a checkout link to register. Ask it about a domain the user already owns somewhere else, and it calls check_domain_transfer instead.

What it’s good for:

• Naming a new product, startup, side project, or rebrand.
• Finding alternatives when the obvious .com is taken - across modern TLDs like .ai, .io, .co.
• Comparing pricing across TLDs before committing to a name.
• Quick “is this name taken?” lookups inside a conversation.
• Telling somebody who already owns a domain whether it could move, what is standing in the way, and what one full term would cost.

New to giving an assistant a live domain lookup? See how AI assistants search domains for a focused walkthrough of what the search returns and where the boundary is, and the transfer check for agents for the same on check_domain_transfer. The server’s public metadata (name, description, endpoint) lives at github.com/just-done/just-domain-mcp.

Claude.ai (web & desktop)

Fastest path: Just Domain is listed in the Claude connector directory - one click from claude.ai, nothing to paste. The manual setup below reaches the identical server.

Connect it from the listing, then start a new conversation and ask: “Find me a short .ai domain for a notes app.”

https://mcp.justdomain.ai/

Just plugin for Claude Code and Cowork

The Just plugin adds the Just Domain server and two skills to Claude Code and Cowork: find-a-name suggests names for the business you are building and checks their domains, and just-domain checks a domain, shows what it costs and gives you a link to register it, or checks whether anything blocks moving a domain you own elsewhere to Just Domain. It is published by Just Done LLC from github.com/just-done/skills.

In Claude Code, run:

/plugin marketplace add just-done/skills
/plugin install just@just-skills
/reload-plugins

In Cowork:

1. In the Claude app or on claude.ai, open Customize, then Plugins.
2. Choose Add, then Add marketplace. Enter just-done/skills and choose Sync.
3. Under Discover, choose Add next to Just., and make sure it is turned on.

Claude Code, server only

claude mcp add just-domain https://mcp.justdomain.ai/ --transport http

After the command completes, run /mcp inside Claude Code to confirm the server is connected. Claude Code also reads a project .mcp.json in the JSON format shown in section 4.

Just Domain is published in the ChatGPT plugin directory. Open Plugins in ChatGPT, search for Just Domain, and install it - there is nothing to paste. Or go straight to the listing:

Then start a new conversation and ask: “Find me a short .ai domain for a notes app.” ChatGPT calls search_domains and renders the results in the embedded UI widget.

Want to see the flow before installing anything? Open a prefilled example prompt in ChatGPT. Without the plugin, ChatGPT answers from memory; with it, every availability check is live.

https://mcp.justdomain.ai/

Building with ChatGPT Sites? Sites hosts your site but doesn’t register domains - see a domain for your ChatGPT site for the two-step connect.

Cursor

One click if Cursor is installed: Add to Cursor (a cursor:// install link with the server URL prefilled). Or add it by hand in ~/.cursor/mcp.json:

{
  "mcpServers": {
    "just-domain": {
      "url": "https://mcp.justdomain.ai/"
    }
  }
}

Any MCP-compatible client

Just Domain follows the standard Streamable HTTP MCP transport. Any client that connects to a hosted MCP server can use it. Clients that read a JSON config (Cursor, Claude Code’s .mcp.json, and others) take the same block:

{
  "mcpServers": {
    "just-domain": {
      "url": "https://mcp.justdomain.ai/"
    }
  }
}

Point your client at https://mcp.justdomain.ai/ with no auth headers. Note the endpoint is served at the host root - there is no /mcp path suffix.

The MCP surface intentionally ships two focused, read-only tools. There are no account-management, billing, DNS, purchase, unlock, or authorization-code tools - keeping the surface minimal makes the assistant’s job easier and the trust boundary obvious.

search_domains · read-only

Checks one or more candidate domain names and returns, for each, whether it’s available, its registration price, its renewal price, and - for available names - a ready-to-open checkout URL. Both prices are totals for one full registration term of that ending, never per-year rates: one year on most endings, two years on .ai, whose registry mandates a two-year term. The term itself comes back as term_years. Do not divide or multiply a returned price by a number of years.

Inputs

• domains - array of fully-qualified names to check (e.g. ["oatmeal.ai", "oatmeal.io", "oatmeal.com"]).

Returns

A results array, one entry per requested name. Each entry is shaped like:

{
  "fqdn": "oatmeal.ai",
  "name": "oatmeal",
  "tld": "ai",
  "available": true,
  "status": "free",
  "premium": false,
  "price":         { "currency": "USD", "formatted": "<full-term total>" },
  "renewal_price": { "currency": "USD", "formatted": "<full-term total>" },
  "term_years": 2,
  "checkout_url": "https://justdomain.ai/checkout?sld=oatmeal&tld=ai&years=2",
  "warnings": []
}

Each price / renewal_price object also carries amount_minor (an integer in the smallest currency unit) alongside the human-readable formatted string. When a domain is unavailable, its entry still appears with available: false and no checkout_url, so the assistant can suggest alternatives without a follow-up call.

check_domain_transfer · read-only

Answers about onedomain the user already owns at another registrar: what would block a transfer, who sponsors it today, whether its DNS keeps answering through a move, and the total price for one full transfer term. Built from two public sources only - the registry’s own record and our registrar’s price list - so it reads nothing about anyone’s account.

Inputs

• domain - required. One fully-qualified name including its ending (e.g. "acme.com"). Not a bare label and not a list: each call reads a third-party registry.

Returns

{
  "domain": "example.com",
  "tld": "com",
  "supported": true,
  "ready": false,
  "checked_at": "2026-09-09T19:25:22Z",
  "blockers": [{ "code": "locked", "detail": "...", "eligible_at": null }],
  "registrar": { "name": "...", "iana_id": "447" },
  "nameservers": ["ns-1.example-dns.org"],
  "dns_continuity": { "case": "independent", "provider": "...", "detail": "..." },
  "price": {
    "amount": "10.46", "currency": "USD", "term_years": 1,
    "term_note": "...", "expected_new_expiry": "2028-09-11", "is_premium": false
  },
  "source": { "rdap": true, "registrar_pricing": true },
  "transfer_url": "https://justdomain.ai/transfer?domain=example.com",
  "next_step": "...",
  "auth_code_policy": "..."
}

An empty blockers list is the only thing that means the domain is ready to move; readyis a convenience over that list and can never disagree with it. The code list is open, so render an unrecognised code’s detail rather than dropping it. price: null means the price could not be read, not that a transfer is free, and source.rdap: false means nothing about the domain was established. Full reference: the transfer check for agents.

Paste any of these into a Claude or ChatGPT conversation with Just Domain connected.

See the full privacy policy and security policy for details.

Stuck, hit a bug, or want a TLD we don’t list yet?

This documentation is a living document. Last updated September 17, 2026.