checker-mcp

@oksigenia/checker-mcp

A domain security and privacy checker exposed as an MCP server. It runs entirely on your machine, makes no telemetry calls, and resolves DNS through Cloudflare DoH instead of Google.

Ask any MCP client to scan a domain and get back a scored report covering the certificate, email authentication, DNS and infrastructure, and web security headers, with a plain remediation for anything that fails.

Why it's different

• Local-first. The server runs over stdio and does its own DNS-over-HTTPS, HTTP, RDAP and TLS lookups. The only network traffic is the checks themselves.
• Zero telemetry. No analytics, no phone-home, no third-party scoring service in the loop.
• Privacy by default. DNS goes to Cloudflare DoH rather than Google, and the reputation check uses Cloudflare's malware/phishing resolver.
• Free software. Licensed GPL-3.0-or-later. Read it, run it, change it, self-host it.

Tools

The server exposes three tools.

check_domain

Scan a domain or URL and return a scored report from real live checks.

// arguments
{
  "domain": "example.com",          // bare domain or full URL
  "categories": ["ssl", "email"],   // optional subset; defaults to all
  "format": "report",               // "report" (default) or "json"
  "lang": "en"                      // "es" or "en"
}

list_checks

List every check grouped by category, with the reason each one matters.

{ "lang": "en" }

explain_check

Explain a single check by id, why it matters, and how to remediate a failure.

{ "check_id": "dmarc", "lang": "en" }

Checks

Seventeen checks across four categories, weighted to a 0-100 score.

Category	Check id	What it verifies
ssl	ssl	SSL/TLS certificate validity and expiry
email	spf	SPF record present and not overly permissive
email	dmarc	DMARC policy and reporting
email	dkim	DKIM signing (common selectors probed)
email	mta_sts	MTA-STS against SMTP downgrade attacks
email	mx	MX records for mail delivery
email	bimi	BIMI brand logo record and VMC
dns	dnssec	DNSSEC signing on the zone
dns	ptr	PTR / forward-confirmed reverse DNS
dns	caa	CAA records restricting certificate issuance
dns	blacklist	Malware/phishing reputation
dns	expiry	Domain registration expiry
dns	whois_redact	WHOIS/RDAP personal-data redaction
web	headers	HTTP security headers (HSTS, CSP, X-Frame-Options, …)
web	csp	Content-Security-Policy quality
web	web_tech	CMS/server version and API exposure
web	hsts_preload	HSTS preload-list status

Run list_checks for the full descriptions, or explain_check for one at a time.

Install

Run it straight from npm with npx:

npx @oksigenia/checker-mcp

Register it with Claude Code:

claude mcp add oksigenia-checker -- npx -y @oksigenia/checker-mcp

Or add it to any MCP client config (works in Claude Desktop, Claude Code, or any MCP client):

{
  "mcpServers": {
    "oksigenia-checker": {
      "command": "npx",
      "args": ["-y", "@oksigenia/checker-mcp"],
      "env": { "OKSIGENIA_LANG": "en" }
    }
  }
}

Then ask: "Check the security of example.com" or "Explain the dmarc check."

Run with Docker

Build and run it as a container. It speaks MCP over stdio, so run it attached to your client's stdin/stdout (-i), not on a port.

docker build -t oksigenia-checker-mcp .
docker run --rm -i oksigenia-checker-mcp

Languages

Reports render in Spanish and English. Set the default with OKSIGENIA_LANG (es or en), or pass lang on any tool call. It defaults to English.

Privacy

The only thing that leaves your machine is the domain name you scan, sent to:

• Cloudflare DoH (cloudflare-dns.com) and Cloudflare's security resolver, for DNS and reputation
• public RDAP (rdap.org), for registration and WHOIS-privacy data
• the HSTS preload API, for preload status
• the target site itself, over HTTPS, to read its certificate and security headers

There is no telemetry, no analytics, and no third-party scoring service. Nothing about your queries is stored or transmitted anywhere else.

Develop

npm install
npm run build       # tsup -> dist/
npm run typecheck   # tsc --noEmit
npm test            # vitest (hermetic, mocked network)
npm run smoke       # spawn the built server and exercise every tool live

Dev watch: npm run dev.

• src/engine.ts — the network engine. Language-agnostic: returns i18n keys, not text. Every check is individually resilient and runChecks never throws.
• src/i18n.ts — es/en dictionaries and t().
• src/index.ts — the MCP server: renders engine keys into the requested language and exposes the three tools.

See CONTRIBUTING.md for the PR flow.

License

GPL-3.0-or-later © Oksigenia SL