ClaudSkills / Engineering / architecture

One Three One Rule

Q: What is a Claude Code skill and how does the One Three One Rule skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. One Three One Rule is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at https://claudskills.com/learn/what-is-skill-md/.

Category: Engineering · Sub-category: architecture · Last updated: 2026-05-21

Structured decision-making framework for technical proposals and trade-off analysis. When the user faces a choice between multiple approaches (architecture decisions, tool selection, refactoring strategies, migration paths), this skill produces a 1-3-1 format: one clear problem statement, three distinct options with pros/cons, and one concrete recommendation with definition of done and implementation plan. Use when the user asks for a "1-3-1", says "give me options", or needs help choosing between competing approaches.

Security AStatic scan found no risk patternsHow grading works ›

About this skill (catalog notes)

One Three One Rule includes worked examples; pricing or quota commentary. The SKILL.md runs to about 639 words, in the catalog's typical mid-range.

License: MIT
Original author: Willard Moore
Indexed lastmod: 2026-05-21
Catalog position: Engineering · architecture
Indexed related skills: 10

How One Three One Rule fits the catalog

One Three One Rule sits in the Engineering category under the architecture sub-topic in the ClaudSkills catalog. There are 10 related skills indexed alongside it; comparing a few before installing usually reveals which fits your workflow best.

These notes are auto-generated from features detected in the SKILL.md file and from this catalog's structure — they aren't part of the source repository.

From the source SKILL.md

Structured decision-making format for when a task has multiple viable approaches and the user needs a clear recommendation. Produces a concise problem framing, three options with trade-offs, and an actionable plan for the recommended path.

What this skill does

One Three One Rule is a community-contributed Claude Code skill in the architecture sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/one-three-one-rule/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use when the user asks for a "1-3-1", says "give me options", or needs help choosing between competing approaches.

Who uses this skill

The One Three One Rule Claude Code skill is built for software engineers, backend developers, full-stack teams, and technical leads building and maintaining production systems. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 158,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/one-three-one-rule
curl -L https://claudskills.com/skills/one-three-one-rule/SKILL.md \
  -o ~/.claude/skills/one-three-one-rule/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/one-three-one-rule/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/one-three-one-rule/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\one-three-one-rule\SKILL.md on Windows. See the full install guide for step-by-step instructions.

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the One Three One Rule Claude Code skill?

Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/one-three-one-rule/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.

What does the One Three One Rule skill do?

Is this skill free to install?

Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.

When should I use the One Three One Rule skill?

Use One Three One Rule when your Claude Code task falls under the Engineering category — specifically in the architecture area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use One Three One Rule" or describe the task and let Claude pick). Browse related skills at /category/engineering/.

What is a Claude Code skill and how does the One Three One Rule skill fit in?

A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. One Three One Rule is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

License: MIT
Author: Willard Moore

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA

Willard Moore. (2026). One Three One Rule [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/one-three-one-rule/

BibTeX

@misc{one-three-one-rule-2026,
  author    = {Willard Moore},
  title     = {One Three One Rule [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/one-three-one-rule/}
}

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Badge

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Security scan

Grade A · scanned 2026-07-23 — free static scan against the OWASP Agentic Skills Top 10.

No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›

✓ Prompt injection
✓ Data exfiltration
✓ Supply chain
✓ Reverse shell
✓ Credentials
✓ Execution
✓ Filesystem
✓ Persistence
✓ Obfuscation
✓ Network

Show this grade on your repo (click to copy):

[![Security: A](https://img.shields.io/badge/Security-A-2e7d32)](https://claudskills.com/skills/one-three-one-rule/#security)

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Browse all Engineering skills → Top 100 skills

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