domain-search

A tool for checking whether internet domain names are registered, using data supplied by domain registries across different endings such as .com or .org.

In plain words
What is it for?
It helps verify whether domains are available, registered, for sale, or expiring, and reports how each result was checked. RDAP is the registries' standard web service for this information.
Why use it?
It avoids common false answers from unreliable whois text or broken lookup routes by requiring each checking method to be validated.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/codecast-sh/codecast/domain-search
Any agent
npx skills add codecast-sh/codecast --skill domain-search
Clone the repo
git clone --depth 1 https://github.com/codecast-sh/codecast

Made for: Claude Code, Codex.

Per session 54 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 990 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00054 $0.00990
Opus 5 $0.00027 $0.00495
Sonnet 5 $0.00011 $0.00198
Haiku 4.5 $0.00005 $0.00099

Measured 3d ago against content hash 4e65048df57d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

domain-search scanned grade A with 1 finding 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 3d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/check-domains.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

2. **Find the endpoint** in the IANA bootstrap: `curl -s https://data.iana.org/rdap/dns.json` maps each TLD to its server. A TLD absent from the file has no RDAP; use registry whois.
packages/cli/src/capabilities/__fixtures__/manifests/skills/domain-search/SKILL.md · 50 lines

How it starts

The opening of the file, as written. The whole thing — 50 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Check availability against registry data, never against parsed whois text alone. Report only verified results, and say which method verified each one.

The one rule that prevents false positives

Every check method must pass a control: a domain you know is registered on the same TLD, through the same route. If the control does not read as "taken", the route is broken and its results are worthless. A broken route returns the same answer as "available" (example failures: rdap.org returns 404 for vine.co, greenhouse.io, and notion.so — all registered). Never report a domain as available from a route with no passing control.

Grepping whois output for "no match" is the classic trap: registrar boilerplate and rate limit text match those patterns. It once reported showtell.com as available when it had been registered since 1995.

Method

  1. RDAP first. RDAP is the registries' official JSON API. HTTP 200 = registered, 404 = available (on a validated route). Prefer direct registry endpoints over the rdap.org proxy, which is slow and misroutes some TLDs.
  2. Find the endpoint in the IANA bootstrap: curl -s https://data.iana.org/rdap/dns.json maps each TLD to its server. A TLD absent from the file has no RDAP; use registry whois.
  3. Registry whois fallback for TLDs without RDAP. Find the server with whois -h whois.iana.org <tld> (the refer: line), then whois -h <server> <domain>. "Domain Name:" present = taken. Still needs a control.
  4. DNS as a fast signal: dig +short NS <domain> — nameservers present proves registered (absence proves nothing). Parking nameservers (afternic, sedo, bodis, parkingcrew) mean the domain is listed for sale on the aftermarket.

Known endpoints and quirks

Registry TLDs Endpoint Quirks
Verisign .com .net https://rdap.verisign.com/com/v1/domain/X (swap com→net) Reliable, fast
Google .app .dev .page .new https://pubapi.registry.google/rdap/domain/X Aggressive rate limits — sleep 5s or more between queries; 429 means retry slower, not "taken"
Identity Digital .ai .studio .video .show .live .media .tools .pub .wtf and many ngTLDs https://rdap.identitydigital.services/rdap/domain/X Reliable
No RDAP .io .sh .so whois -h whois.nic.io / whois.nic.sh / whois.nic.so rdap.org silently 404s these — never use it for them
.co .co whois -h whois.registry.co Not whois.nic.co; rdap.org misroutes .co

Read the full file on GitHub · 50 lines

Files

What ships with it

1 file 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.

Changes

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.

  1. 3d ago First seen · 50 lines · 54 tokens per session scan A 4e65048df57d

Subscribe to this mod's changes

domain-search is a skill published in the GitHub repository codecast-sh/codecast (30 stars, last pushed 3d ago), licensed MIT. It adds 54 tokens to every session and 990 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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