ClaudSkills / Engineering / code-quality

Designing Deep Modules

Q: What is a Claude Code skill and how does the Designing Deep Modules 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. Designing Deep Modules 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: code-quality · Last updated: 2026-05-21

type:review

Guides designing, reviewing, and refactoring modules for depth — maximizing functionality hidden behind minimal interfaces. Analyzes module boundaries, identifies shallow modules and classitis, applies deep module heuristics (pull complexity downward, define errors out of existence, design for the common case), and produces refactoring plans. Covers information hiding, leaky abstractions, and abstraction boundaries based on Ousterhout's A Philosophy of Software Design. Use when designing module interfaces, reviewing code for shallow abstractions, refactoring pass-through layers, evaluating API surface area, reducing interface complexity, or applying deep module principles at any scale (functions, classes, packages, services, APIs).

From the source SKILL.md

A deep module hides substantial complexity behind a small, simple interface. A shallow module exposes an interface nearly as complex as its implementation. "Module" means any abstraction boundary: function, class, package, service, or API.

What this skill does

Designing Deep Modules is a community-contributed Claude Code skill in the code-quality sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/designing-deep-modules/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use when designing module interfaces, reviewing code for shallow abstractions, refactoring pass-through layers, evaluating API surface area, reducing interface complexity, or applying deep module principles at any scale (functions, classes, packages, services, APIs).

Who uses this skill

The Designing Deep Modules 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 117,000+ 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/designing-deep-modules
curl -L https://claudskills.com/skills/designing-deep-modules/SKILL.md \
  -o ~/.claude/skills/designing-deep-modules/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/designing-deep-modules/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/designing-deep-modules/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\designing-deep-modules\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 Designing Deep Modules Claude Code skill?

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

What does the Designing Deep Modules 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 Designing Deep Modules skill?

Use Designing Deep Modules when your Claude Code task falls under the Engineering category — specifically in the code quality 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 Designing Deep Modules" or describe the task and let Claude pick). Browse related skills at /category/engineering/.

What is a Claude Code skill and how does the Designing Deep Modules 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. Designing Deep Modules 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

Source: https://github.com/msewell/agent-stuff/blob/HEAD/skills/designing-deep-modules/SKILL.md
Author: msewell

Cite this skill

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

APA

msewell. (2026). Designing Deep Modules [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/designing-deep-modules/

BibTeX

@misc{designing-deep-modules-2026,
  author    = {msewell},
  title     = {Designing Deep Modules [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/designing-deep-modules/}
}

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