Lean Specification

Q: What is a Claude Code skill and how does the Lean Specification 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. Lean Specification is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Product category. Learn more at https://claudskills.com/learn/what-is-skill-md/.

Category: Product · Sub-category: prd-spec · Last updated: 2026-05-30

type:review type:integration

USE FOR: Design theorem specifications for Lean 4 proofs. Use when planning new theorems, lemmas, definitions, or tactics. Covers the three-part specification (requirements, design, documentation), lifecycle management, dependency analysis, and integration with the review council. DO NOT USE FOR: actual proof writing (use @lean-proof); requirement extraction (use @lean-doc-requirements); review (use @lean-proof-review). TRIGGERS: specification, theorem spec, three-part spec, lemma plan, tactic plan.

About this skill (catalog notes)

Lean Specification is published as a SKILL.md file in this catalog. The SKILL.md is on the shorter side at about 280 words.

Source: github.com/r-irbe/proof-skills
License: Apache-2.0
Original author: r-irbe
Indexed lastmod: 2026-05-30
Catalog position: Product · prd-spec
Indexed related skills: 10

How Lean Specification fits the catalog

Lean Specification sits in the Product category under the prd-spec 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 process for specifying theorems before implementation. Every theorem passes through Specify → Design → Implement → Review → Merge, with each stage tracked by document templates.

What this skill does

Lean Specification is a community-contributed Claude Code skill in the prd-spec sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/lean-specification/ and loads when your prompt matches the skill's trigger.

When to invoke it: Use when planning new theorems, lemmas, definitions, or tactics. Covers the three-part specification (requirements, design, documentation), lifecycle management, dependency analysis, and integration with the review council.

Who uses this skill

The Lean Specification Claude Code skill is built for product managers, product designers, and cross-functional teams planning, shipping, and measuring product features. 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/lean-specification
curl -L https://claudskills.com/skills/lean-specification/SKILL.md \
  -o ~/.claude/skills/lean-specification/SKILL.md

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

Skills live at ~/.claude/skills/lean-specification/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\lean-specification\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 Lean Specification Claude Code skill?

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

What does the Lean Specification 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 Lean Specification skill?

Use Lean Specification when your Claude Code task falls under the Product category — specifically in the prd spec 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 Lean Specification" or describe the task and let Claude pick). Browse related skills at /category/product/.

What is a Claude Code skill and how does the Lean Specification 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. Lean Specification is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Product category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Source: https://github.com/r-irbe/proof-skills/blob/HEAD/skills/lean-specification/SKILL.md
License: Apache-2.0
Author: r-irbe
Website: https://github.com/r-irbe/proof-skills

Cite this skill

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

APA

r-irbe. (2026). Lean Specification [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/lean-specification/

BibTeX

@misc{lean-specification-2026,
  author    = {r-irbe},
  title     = {Lean Specification [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/lean-specification/}
}

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