/domain-check

name: domain-check
description: 'Check domain availability (Available/Taken) for any TLD with confidence scoring, SSL certificate inspection, and IP resolution. Uses 5+ sources in parallel — RDAP, WHOIS (TLD-specific patterns for 30+ ccTLDs/gTLDs, IANA fallback for unknown TLDs), authoritative DNS NS lookup as GDPR tiebreaker for .de/.eu/.at/.ch/.es, DNS A/AAAA, HTTP reachability, and TLS certificate validation. Returns a clear binary verdict; when Taken, inline includes registrar, expiration date (or note if registry redacts under GDPR), nameservers, server IPs, and full SSL cert details. Single-domain or bulk-async (30 domains in ~10s). Stateless, stdlib-only, runs identically on Linux, macOS, and Windows. Use when the user asks if a domain is free/taken/available/registered, wants WHOIS or RDAP info, SSL certificate details, or to resolve a URL/domain to its server IPs. Triggers — "is X.com free", "check this domain", "bulk domain check", "SSL cert of X", "what IP does X resolve to", "domain availability", "ist X.de frei", "domain prüfen", "Belegt oder frei".'

domain-check

Platform-independent domain checker. Answers the binary question **Available / Taken** with high confidence (100% when all sources agree) and, for taken domains, returns the most relevant details inline: SSL certificate, server IP, expiration date.

MANDATORY READ — ANY DOMAIN-NAMING REQUEST

**As the very first action — before generating, recommending, suggesting, scoring, or curating ANY domain names — you MUST `Read references/naming_guide.md` in full.** Non-skippable. One Read tool call, ~3,300 words.

This rule fires on **all** of these triggers, not just on `suggest`:

• "schlag mir Domains vor", "suggest domains", "give me domain ideas"
• "good name for X", "guter Name für X", "creative domain names"
• "what should I call X", "wie soll ich X nennen"
• "Domain-Tipps", "domain tips", "naming ideas"
• bare `suggest` subcommand invocations
• any free-form follow-up where the user asks for a curated list of names

**The guide is the single source of truth. The Python `score_name()` heuristics are a sanity helper, NOT a substitute for the guide.** Skipping the guide produces generic `voicebotify` / `cloudhub` slop that doesn't match the user's actual project.

**Workflow for any naming request:** 1. `Read references/naming_guide.md` — non-skippable, before any candidate is written 2. Pick 2–3 patterns from the guide that fit the user's project (e.g. "AI phone bot" → Hybrid Neoclassic + Action-Verb + Made-up-Phonetic, NOT just `voicebot+ify`) 3. Hand-curate a candidate list using the guide's brainstorming techniques (semantic web, mood board, free association, grandma test, 1AM bar test) 4. Run `bulk` to check availability — `suggest` output is only a starting point, never the final list 5. Apply the don't-list (no hyphens, no digit substitutions, no false friends, no typo-squat distance ≤1) 6. Present 8–15 curated finalists with rationale + buy_links, not 200 raw heuristic outputs

Requirements

**No dependencies. No venv. No pip/uv/pipx required.**

The entire skill runs on the **Python ≥ 3.11 standard library** (needed for `dict | None` syntax and `asyncio.to_thread`). Module imports used by the skill: `argparse, asyncio, dataclasses, datetime, hashlib, io, json, os, pathlib, re, secrets, socket, ssl, struct, sys, tempfile, time, typing, urllib`. All stdlib.

If you run an exotic Python build without the SSL module, only the `ssl` subcommand will fail; the rest still works.

Quick Start

All commands are run from this skill's directory (the agent will cd there automatically). Same invocations on Linux, macOS, and Windows:

python3 scripts/domain_check.py check example.com
python3 scripts/domain_check.py bulk example.com example.org example.net
python3 scripts/domain_check.py ssl example.com
python3 scripts/domain_check.py resolve https://example.com/path

On Windows, use `python` instead of `python3` if needed.

Subcommands

`check <domain>`

Single-domain check, JSON output.

**For "Taken"** the response contains:

• `verdict: "Taken"`, `confidence`, `summary`
• `expiration_date` (ISO date) or `expiration_note` (e.g. "DENIC confirms the registration but does not expose the expiry date publicly (GDPR).")
• `registrar`, `nameservers`, `ip_addresses`
• `ssl: { issuer, subject, valid_to, days_until_expiry, fingerprint_sha256, ip_address, matches_hostname, ... }`
• `evidence: [...]` — list of all 5–6 sources with `source`/`strength`/`reason`

**For "Available"** a compact response: `verdict: "Available"`, `confidence`, `summary`, `evidence`. No SSL/IP blocks (irrelevant).

**For "Reserved"** / **"Unclear"**: `verdict` plus rationale in `summary` plus `evidence` for diagnosis.

`bulk <d1> <d2> …` OR `--file <path>` OR `--stdin`

Up to 8 domains in parallel. NDJSON output (one line per domain) — pipe-friendly. Alternatives:

• `--format=json` → a single JSON array
• `--format=table` → human-readable table

python3 scripts/domain_check.py bulk --file domains.txt --format=table
echo -e "example.com\nexample.org" | python3 scripts/domain_check.py bulk --stdin

`ssl <hostname> [--port 443]`

SSL certificate only. Returns issuer, subject, SAN, valid_from/to, days_until_expiry, SHA-256 fingerprint, protocol, cipher, and the effective IP of the TLS connection.

`resolve <url-or-host>`

Extracts the hostname from a URL and resolves IPv4 + IPv6, plus reverse DNS for the first 3 IPs. Accepts `https://example.com/path`, `example.com:443`, `example.com`.

What is the "TLD-aware decision tree"?

Whether a domain is "Available" or "Taken" depends on **which** sources are authoritative for the given TLD:

• **gTLDs** (`.com`, `.net`, `.io`, `.ai`, `.app`, `.pro`, `.club`, …): RDAP is mandatory under ICANN — RDAP no-object = 100% available.
• **GDPR ccTLDs** (`.de`, `.eu`, `.at`, `.ch`, `.es`, …): the registry typically redacts RDAP/WHOIS entirely. Here an **authoritative