regex-builder

regex-builder is a command for Claude Code from Amey-Thakur/AI-SKILLS. It costs 17 tokens per session (287 once invoked), scanned A, original, MIT.

A regular-expression builder that turns a plain-language matching rule into a pattern. A regular expression is a compact pattern used to find or validate text, and the add-on explains the result with test cases.

In plain words
What is it for?
Use it to create and understand text-matching patterns, test strings that should or should not match, and spot edge cases such as empty input or nested data.
Why use it?
It reduces mistakes when writing patterns and makes their behavior easier to check, including engine differences and cases where a regular expression is the wrong tool.

Command for Claude Code

Written for Claude Code: argument-hint in frontmatter.

Good fit Use it to create and understand text-matching patterns, test strings that should or should not match, and spot edge cases such as empty input or nested data.

Compare 6 commands from other repositories ↓
Install with agentmods
npx agentmods add commands/amey-thakur/ai-skills/regex-builder
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.

Clone the repo
git clone --depth 1 https://github.com/Amey-Thakur/AI-SKILLS

Made for: Claude Code.

Wrote 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.

agentmods badge for regex-builder

README.md
[![agentmods](https://agentmods.dev/badge/commands/amey-thakur/ai-skills/regex-builder/github.svg)](https://agentmods.dev/commands/amey-thakur/ai-skills/regex-builder)
Your own site
<a href="https://agentmods.dev/commands/amey-thakur/ai-skills/regex-builder"><img src="https://agentmods.dev/badge/commands/amey-thakur/ai-skills/regex-builder/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.

agentmods 80×15 button for regex-builder

Your own site · 80×15
<a href="https://agentmods.dev/commands/amey-thakur/ai-skills/regex-builder"><img src="https://agentmods.dev/badge/commands/amey-thakur/ai-skills/regex-builder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 17 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 287 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00017 $0.00287
Opus 5 $0.00009 $0.00143
Sonnet 5 $0.00003 $0.00057
Haiku 4.5 $0.00002 $0.00029

Measured 6d ago against content hash 29f4e382746b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-13, from the pricing page.

Security

Grade A, and why

regex-builder 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 6d 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.

commands/regex-builder.md · 34 lines

What it actually says

You were invoked as a slash command. The user's input:

$ARGUMENTS

Use that input to fill this prompt's variables (take the main content, topic, or task from it; ask only if a required value is missing and not supplied), then follow the prompt exactly.


Build a regular expression for: {requirement}

Flavor: {flavor}

Provide:

  1. The regex, in a code block, ready to use.
  2. A breakdown: explain each part of the pattern in one line, so it can be understood and modified.
  3. Test cases: 3-4 strings that SHOULD match and 3-4 that should NOT, so the behavior is verifiable. Note any tricky edge case (empty string, unicode, anchoring, greedy vs lazy) the pattern handles or deliberately does not.
  4. Flavor notes: if the pattern uses features that differ across engines (lookbehind, named groups, \d semantics), say so.

Rules: prefer a readable pattern over a clever one; if the requirement is better served by NOT using regex (parsing structured data, matching nested structures), say so and suggest the alternative. Warn if the pattern risks catastrophic backtracking.

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. 6d ago First seen · 34 lines · 17 tokens per session scan A 29f4e382746b

Subscribe to this mod's changes

regex-builder is a command published in the GitHub repository Amey-Thakur/AI-SKILLS (7 stars, last pushed 7d ago), licensed MIT. It adds 17 tokens to every session and 287 once invoked, about $0.0001 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 2026-09-06.