Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add georgekhananaev/claude-skills-vault --skill domain-checkergit clone --depth 1 https://github.com/georgekhananaev/claude-skills-vaultWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/georgekhananaev/claude-skills-vault/domain-checker)<a href="https://agentmods.dev/skills/georgekhananaev/claude-skills-vault/domain-checker"><img src="https://agentmods.dev/badge/skills/georgekhananaev/claude-skills-vault/domain-checker/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/georgekhananaev/claude-skills-vault/domain-checker"><img src="https://agentmods.dev/badge/skills/georgekhananaev/claude-skills-vault/domain-checker.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Anti-Refusal · line 144 Skill instructs the agent to omit warnings, disclaimers, or ethical commentary. Stripping safety caveats hides risk from the user and is a common jailbreak preamble.Fix: Remove instructions that suppress warnings, disclaimers, or ethical commentary. Let the agent surface safety-relevant caveats to the user.
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00115 | $0.02970 |
| Opus 5 | $0.00057 | $0.01485 |
| Sonnet 5 | $0.00023 | $0.00594 |
| Haiku 4.5 | $0.00012 | $0.00297 |
Grade A, and why
domain-checker scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 12d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 206 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Domain Checker
Check domain availability in bulk using RDAP (Registration Data Access Protocol) as the primary signal, with WHOIS and DNS fallbacks. Python stdlib only.
When to Use
- User asks "is
<domain>available / taken / registered?" - User wants to check many domains at once (a list, a file, names piped in)
- User wants to test a brand name across many TLDs (
acme.com,acme.net,acme.io, …) - User wants machine-readable output (CSV/JSON) for further processing
- User wants only available (or only taken) results filtered
Do NOT use for: WHOIS contact lookup (this skill only checks existence), DNS record inspection (use dig), trademark/legal availability (this only checks registration status).
How It Works
- RDAP first — fetches the IANA RDAP bootstrap (
data.iana.org/rdap/dns.json, cached 24h in~/.cache/domain-checker/) to find the authoritative RDAP server for each TLD.HTTP 404= available,HTTP 200= taken. - WHOIS fallback — if RDAP is unavailable for a TLD (notably
.io, some ccTLDs) or returns ambiguous, shells out to the localwhoisCLI and matches well-known "not found"/"registered" patterns. - DNS — optional, weak signal. Resolves A/AAAA records. Confirms "taken" only — registered-but-unhosted domains will show no DNS, so DNS alone cannot prove "available".
After the primary check, three enrichment passes refine accuracy:
- Aftermarket detection — parses the RDAP response we already fetched. Flags
aftermarketwhen the registrant/entity name matches a known reseller (HugeDomains, Sedo, Afternic, Dan.com, NameJet, DropCatch, …) OR when the nameservers match parking patterns (sedoparking.com,parkingcrew.net,namefind.com,afternic.com,bodis.com, …). Free — no extra requests. - RDAP status parsing — surfaces
pendingDelete/redemptionPeriod/clientHold/serverHoldas a separateexpiringstatus (these domains may drop and become available within ~30 days). - Premium-likely hint — for
availableresults, appends a warning when the name is short (≤5chars on.ai/.io/.app/.dev/.co/.tv/.me/.cc/.tech/.xyzor≤3chars on.com/.net/.org). This is a heuristic, not a hard claim — the registrar checkout has the real price. - Optional HTTP sale-page probe (
--probe-sale) — fetches the homepage and looks for "for sale" / Sedo / Dan.com / HugeDomains / Afternic markers. Reclassifiestaken→aftermarketon a hit. Off by default; adds ~1s per checked domain.
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 12d ago First seen · 206 lines · 115 tokens per session scan A dd62d7743522
domain-checker is a skill published in the GitHub repository georgekhananaev/claude-skills-vault (28 stars, last pushed 1mo ago), licensed MIT. It adds 115 tokens to every session and 2,970 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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