Decisive registry record
A direct registry source returned a current registration record.
MCP domain checker · remote server live
Check domains from your agent, with evidence attached.
NamingSignal's MCP server lets Claude Code, Codex, and any Streamable HTTP MCP client check domain availability mid-conversation. Every result keeps its source, check time, and evidence state, so an agent can reason about what is known instead of repeating a green badge.
{
"results": [{
"name": "offhook",
"score": 74,
"domains": [
"com: registered (rdap.verisign.com, 2026-07-13)",
"dev: likely_available (registry RDAP, 2026-07-13)",
"io: unknown (timeout, 2026-07-13)"
],
"verifyUrl": "https://porkbun.com/checkout/search?q=offhook.com"
}]
}Calibrated absence
Registry not-found is trusted only after the provider recognizes a known-registered control domain on the same TLD.
Failure stays unresolved
Timeout, rate limit, unsupported TLD, or failed calibration. Unknown never turns into available.
Registrar check is yours
Price, premium status, and current registrability are verified by a person at a registrar, via the link each result includes.
What it returns
Compact JSON built for agent context
Results are one compact text block per call: name, score, one evidence line per domain with provider and check date, hard blockers when present, and a registrar verification link. No pretty-printed duplication flooding the context window. Verbose evidence objects are opt-in.
How it differs from registrar MCPs
Read-only and registrar-neutral
Registrar MCP servers exist to sell inventory, and some can complete purchases from the conversation. NamingSignal's server is evidence-first: it checks registries directly, marks what it cannot verify as unknown, and hands the purchase to whichever registrar you choose. No tool can spend money.
More than domains
Part of a full naming workflow
The same server compiles naming briefs, generates candidate fields, checks developer namespaces, and researches finalists with sources. Domain checking is one of five read-only tools sharing one evidence contract.
Technical note
Why a 404 is not availability.
Read the known-registered canary method behind the likely_available state.
Questions
MCP domain checker FAQ
What is an MCP domain checker?
MCP (Model Context Protocol) is the standard that lets agents like Claude Code and Codex call external tools. An MCP domain checker exposes domain availability checks as MCP tools, so an agent can check names during a conversation instead of you switching to a registrar website.
Does the checker ever guarantee a domain is available?
No. A registry not-found response becomes likely unregistered only after the same provider passes a calibration test against a domain known to be registered. Registrar purchaseability, price, and premium status still require a manual check, and the tools return a verification link for exactly that step.
Can it buy domains for me?
No, by design. Every tool is read-only. The server never purchases, reserves, registers, or files anything. It returns registrar search links so a person completes the purchase wherever they prefer.
How many names can one call check?
check_names accepts up to 100 names and up to five TLDs per call, bounded at 150 name and TLD combinations. A domain combination costs one Naming Credit, and the free plan includes 15,000 credits per month.
What do I need to connect it?
A free NamingSignal account and an API key from namingsignal.com/developers/keys. The remote server at https://namingsignal.com/mcp works with any MCP client that supports Streamable HTTP with an Authorization header.