Skill Distiller

Skill Distiller

Turn a pile of source material into a reusable AgentSkill.

Pre-flight: Check dependencies

Before ingesting YouTube sources, verify yt-dlp is installed:

which yt-dlp || echo "NOT INSTALLED"

If not installed, prompt the user to install it before proceeding with YouTube ingestion:

• macOS: brew install yt-dlp
• Linux: pip install yt-dlp
• Windows: winget install yt-dlp

If the user only has URLs and local files (no YouTube), skip this check.

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Workflow

1) Define the target skill

Collect:

• Skill name (lowercase + hyphens)
• What it should help with (2–5 concrete user requests it should handle)
• What it should not do (boundaries)

Scope check — should this be one skill or many?

If the topic covers 3+ distinct categories or 5+ independent tactics, split it:

• One skill = the index (SKILL.md with a quick-reference table + priority tiers)
• Individual rules = one file per rule in a rules/ directory (each with: why it matters, bad example, good example)

Example pattern (see vercel-react-best-practices for a live implementation):

my-skill/
├── SKILL.md          # Index: categories, priority table, rule list
└── rules/
    ├── rule-one.md   # Why + bad + good
    ├── rule-two.md
    └── ...

The agent loads SKILL.md first (lightweight), then pulls individual rule files only when relevant. This keeps context lean and lets each rule be self-contained.

2) Ingest sources into a corpus folder

Use the bundled ingestion scripts to create a local corpus you can cite and reuse.

YouTube transcript → text

python3 ~/.claude/skills/skill-distiller/scripts/get_youtube_transcript.py "https://www.youtube.com/watch?v=VIDEO_ID" > out.txt

URL → rough readable text

python3 ~/.claude/skills/skill-distiller/scripts/extract_url_text.py "https://example.com/article" > out.txt

Local file → text

python3 ~/.claude/skills/skill-distiller/scripts/read_text_file.py /path/to/file.md > out.txt

Save raw output directly into the new skill's folder (not /tmp — it needs to persist):

/
  references/
    sources.md
    knowledge.md
    raw/
      001-*.txt
      002-*.txt

Coverage check before distilling: After ingesting, ask yourself — do the sources actually cover the topic well enough? If there are obvious gaps (e.g. you have tactics but no data on results, or theory but no practical examples), fetch additional sources before moving on. Better to have complete coverage than to distill incomplete material.

3) Distill (synthesize) into references

Create references/knowledge.md with:

• Overview + glossary
• Processes/checklists
• Gotchas/anti-patterns
• Canonical templates/snippets (if applicable)

Create references/sources.md with:

• Bullet list of every source (URL, title, date captured)
• Notes about source reliability (official docs vs opinion)

Keep SKILL.md lean; put depth in references/.

4) Generate the new skill folder

For detailed guidance on skill structure, writing style, and best practices, read [../skill-creator/SKILL.md](../skill-creator/SKILL.md).

Create the new skill folder (name must match the skill):

• /SKILL.md (frontmatter: name, description)
• references/ for the distilled knowledge
• rules/ if the topic was split into individual rules (see scope check above)
• scripts/ only when deterministic tooling is needed
• assets/ for templates, images, or files used in output (not loaded into context)

Description format: Write the description in third-person with trigger keywords. The agent uses it to decide when to activate the skill — it should say when to use it, not what it does:

# Good — tells the agent when to activate
description: "React performance optimization guidelines. This skill should be used when writing, reviewing, or refactoring React components."

# Bad — describes the skill instead of triggering it
description: "Contains best practices for React performance."

5) Test the skill

Dry-run with 2–3 realistic prompts and verify it:

• Uses the references appropriately
• Doesn’t hallucinate beyond the corpus
• Has clear refusal/boundary behavior when outside scope

Requirements / Notes

• YouTube transcript fetching requires yt-dlp in PATH. Install with:
• macOS: brew install yt-dlp
• Linux: pip install yt-dlp or check yt-dlp releases
• Windows: winget install yt-dlp or download from releases
• extract_url_text.py is intentionally dependency-light (stdlib only); it's "good enough" for most articles but not perfect.
• All Python scripts require Python 3.8+.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: mcart13
• Source: mcart13/skill-distiller
• License: MIT

Install and usage instructions live in the source repository linked above.