---

name: create-skill locale: caveman source_locale: en source_commit: 82c77053 fence_basis_commit: 82c77053 translator: "Julius Brussee homage — caveman" translation_date: "2026-04-19" description: > Create a new SKILL.md file following the Agent Skills open standard (agentskills.io). Covers frontmatter schema, section structure, writing effective procedures with Expected/On failure pairs, validation checklists, cross-referencing, and registry integration. Use when codifying a repeatable procedure for agents, adding a new capability to the skills library, converting a guide or runbook into agent-consumable format, or standardizing a workflow across projects or teams. license: MIT allowed-tools: Read Write Edit Bash Grep Glob metadata: author: Philipp Thoss version: "1.2" domain: general complexity: intermediate language: multi tags: meta, skill, agentskills, standard, authoring

Create a New Skill

Author SKILL.md file that agentic systems can consume to run a specific procedure.

When Use

• Codifying repeatable procedure agents should follow
• Adding new capability to skills library
• Converting guide, runbook, or checklist into agent-consumable format
• Standardizing workflow across projects or teams

Inputs

• Required: Task skill should accomplish
• Required: Domain classification — one of 48 domains in skills/_registry.yml: r-packages, jigsawr, containerization, reporting, compliance, mcp-integration, web-dev, git, general, citations, data-serialization, review, bushcraft, esoteric, design, defensive, project-management, devops, observability, mlops, workflow-visualization, swarm, morphic, alchemy, tcg, intellectual-property, gardening, shiny, animal-training, mycology, prospecting, crafting, library-science, travel, relocation, a2a-protocol, geometry, number-theory, stochastic-processes, theoretical-science, diffusion, hildegard, maintenance, blender, visualization, 3d-printing, lapidary, versioning
• Required: Complexity level (basic, intermediate, advanced)
• Optional: Source material (existing guide, runbook, working example)
• Optional: Related skills to cross-reference

Steps

Step 1: Create Directory

Each skill lives in own directory:

mkdir -p skills/<skill-name>/

Naming conventions:

• Use lowercase kebab-case: submit-to-cran, not SubmitToCRAN
• Start with verb: create-, setup-, write-, deploy-, configure-
• Be specific: create-r-dockerfile not create-dockerfile

Got: Directory skills/<skill-name>/ exists. Name follows lowercase kebab-case starting with verb.

If fail: Name does not start with verb? Rename directory. Check naming conflicts: ls skills/ | grep <keyword> to ensure no existing skill has overlapping name.

Step 2: Write YAML Frontmatter

---
name: skill-name-here
description: >
  One to three sentences plus key activation triggers. Must be clear
  enough for an agent to decide whether to activate this skill from
  the description alone. Max 1024 characters. Start with a verb.
license: MIT
allowed-tools: Read Write Edit Bash Grep Glob  # optional, experimental
metadata:
  author: Philipp Thoss
  version: "1.0"
  domain: general
  complexity: intermediate
  language: R | TypeScript | Python | Docker | Rust | multi
  tags: comma, separated, lowercase, tags
---

Required fields: name, description

Optional fields: license, allowed-tools (experimental), metadata, compatibility

Metadata conventions:

• complexity: basic (< 5 steps, no edge cases), intermediate (5-10 steps, some judgment), advanced (10+ steps, big domain knowledge)
• language: primary language; use multi for cross-language skills
• tags: 3-6 tags for discovery; include domain name

Got: YAML frontmatter parses without errors, name matches directory name, description under 1024 characters with clear activation triggers.

If fail: Validate YAML. Check matching --- delimiters, proper quoting of version strings (e.g., "1.0" not 1.0), right > multi-line folding syntax for description field.

Step 3: Write the Title and Introduction

# Skill Title (Imperative Verb Form)

One paragraph: what this skill accomplishes and the value it provides.

Title should match name but in human-readable form. "Submit to CRAN" not "submit-to-cran".

Got: Top-level # heading in imperative form followed by concise paragraph stating what skill accomplishes.

If fail: Title reads as noun phrase, not verb phrase? Rewrite. "Package Submission" becomes "Submit to CRAN."

Step 4: Write "When to Use"

List 3-5 trigger conditions — concrete scenarios where agent should activate this skill:

## When to Use

- Starting a new R package from scratch
- Converting loose R scripts into a package
- Setting up a package skeleton for collaborative development

Write from agent's perspective. These are conditions agent checks to decide activation.

Note: Most important trigger conditions should also appear in description frontmatter field. Read during discovery phase before full body loaded. ## When to Use section gives extra detail and context.

Got: 3-5 bullet points describing concrete, observable conditions under which agent should activate this skill.

If fail: Triggers feel vague ("when something needs to be done")? Rewrite from agent's perspective: what observable state or user request would trigger activation?

Step 5: Write "Inputs"

Separate required from optional. Be specific about types and defaults:

## Inputs

- **Required**: Package name (lowercase, no special characters except `.`)
- **Required**: One-line description of the package purpose
- **Optional**: License type (default: MIT)
- **Optional**: Whether to initialize renv (default: yes)

Got: Inputs section clearly separates required from optional params. Each has type hint and default value where applicable.

If fail: Parameter's type ambiguous? Add concrete example in parentheses: "Package name (lowercase, no special characters except .)".

Step 6: Write "Procedure"

Core of skill. Each step follows this pattern:

### Step N: Action Title

Context sentence explaining what this step accomplishes.

\```language
concrete_code("that the agent can execute")
\```

**Expected:** What success looks like. Be specific — file created, output matches pattern, command exits 0.

**On failure:** Recovery steps. Don't just say "fix it" — provide the most common failure cause and its resolution.

Writing effective steps:

• Each step independently verifiable
• Include actual code, not pseudocode
• Put most common path first, edge cases in "On failure"
• 5-10 steps is sweet spot. Under 5 may be too vague; over 12 should split into multiple skills.
• Reference real tools and real commands, not abstract descriptions

Writing for translation:

• Target ~400 lines maximum for English skills. German expands 10-20%, some CJK translations expand more — 400-line English source stays under 500 after translation.
• Dodge idioms and culturally-specific examples that translate poorly.
• Keep prose concise and direct — shorter sentences translate better.

Got: Procedure section has 5-12 numbered steps, each with concrete code, **Expected:** outcome, **On failure:** recovery action.

If fail: Step lacks code? Add actual command or configuration. Expected/On failure missing? Write now — every step that can fail needs both.

Step 7: Write "Validation"

Checklist agent runs after completing procedure:

## Validation

- [ ] Criterion 1 (testable, binary pass/fail)
- [ ] Criterion 2
- [ ] No errors or warnings in output

Each item must be objectively verifiable. "Code is clean" is bad. "devtools::check() returns 0 errors" is good.

Got: Markdown checklist (- [ ]) with 3-8 binary pass/fail criteria agent can verify programmatically or by inspection.

If fail: Replace subjective criteria with measurable ones. "Well-documented" becomes "All exported functions have @param, @return, @examples roxygen tags."

Step 8: Write "Common Pitfalls"

3-6 pitfalls with cause and avoidance:

## Common Pitfalls

- **Pitfall name**: What goes wrong and how to avoid it. Be specific about the symptom and the fix.

Draw from real experience. Best pitfalls are ones wasting big time, non-obvious.

Got: 3-6 pitfalls, each with bold name, description of what goes wrong, how to dodge it.

If fail: Pitfalls feel generic ("be careful with X")? Make specific: name symptom, cause, fix. Draw from actual failure scenarios met during development or testing.

Step 9: Write "Related Skills"

Cross-reference 2-5 skills commonly used before, after, or alongside this one:

## Related Skills

- `prerequisite-skill` - must be done before this skill
- `follow-up-skill` - commonly done after this skill
- `alternative-skill` - alternative approach to the same goal

Use skill name field (kebab-case), not title.

Got: 2-5 related skills listed with kebab-case IDs and brief descriptions of relationship (prerequisite, follow-up, alternative).

If fail: Verify each referenced skill exists: ls skills/<skill-name>/SKILL.md. Drop any references to skills renamed or removed.

Step 10: Add to Registry

Edit skills/_registry.yml. Add new skill under right domain:

- id: skill-name-here
  path: skill-name-here/SKILL.md
  complexity: intermediate
  language: multi
  description: One-line description matching the frontmatter

Update total_skills count at top of registry.

Got: New entry shows in skills/_registry.yml under right domain. total_skills count matches actual number of skill directories on disk.

If fail: Count skills on disk with find skills -name SKILL.md | wc -l. Compare against total_skills in registry. Verify id field matches directory name exactly.

Step 11: Add Citations (Optional)

Skill based on established methodologies, research papers, software packages, standards? Add citation subfiles to references/ directory:

mkdir -p skills/<skill-name>/references/

Create two files:

• references/CITATIONS.bib — Machine-readable BibTeX (source of truth)
• references/CITATIONS.md — Human-readable rendered references for GitHub browsing

% references/CITATIONS.bib
@article{author2024title,
  author  = {Author, First and Other, Second},
  title   = {Paper Title},
  journal = {Journal Name},
  year    = {2024},
  doi     = {10.xxxx/xxxxx}
}

<!-- references/CITATIONS.md -->
# Citations

References underpinning the **skill-name** skill.

1. Author, F., & Other, S. (2024). *Paper Title*. Journal Name. https://doi.org/10.xxxx/xxxxx

Citations optional — add when provenance tracking matters (academic methods, published standards, regulatory frameworks).

Handling references/ in translations: Prose descriptions in references/EXAMPLES.md should translate. references/CITATIONS.bib stays English (BibTeX is language-neutral). Translations may symlink to English references/ directory if content is code-only.

Got: Both files exist. .bib parses as valid BibTeX.

If fail: Validate BibTeX syntax with bibtool -d references/CITATIONS.bib or online validator.

Step 12: Validate Skill

Run local validation checks before committing:

# Check line count (must be ≤500)
lines=$(wc -l < skills/<skill-name>/SKILL.md)
[ "$lines" -le 500 ] && echo "OK ($lines lines)" || echo "FAIL: $lines lines > 500"

# Check required frontmatter fields
head -20 skills/<skill-name>/SKILL.md | grep -q '^name:' && echo "name: OK"
head -20 skills/<skill-name>/SKILL.md | grep -q '^description:' && echo "description: OK"

Got: Line count ≤500. All required fields present.

If fail: Over 500 lines? Apply progressive disclosure — extract large code blocks (>15 lines) to references/EXAMPLES.md:

mkdir -p skills/<skill-name>/references/

Move extended code examples, full configuration files, multi-variant examples to references/EXAMPLES.md. Add cross-reference in SKILL.md: See [EXAMPLES.md](references/EXAMPLES.md) for complete configuration examples. Keep brief inline snippets (3-10 lines) in main SKILL.md. CI workflow at .github/workflows/validate-skills.yml enforces these limits on all PRs.

Step 13: Create Slash Command Symlinks

Create symlinks so Claude Code discovers skill as /slash-command:

# Project-level (available in this project)
ln -s ../../skills/<skill-name> .claude/skills/<skill-name>

# Global (available in all projects)
ln -s /mnt/d/dev/p/agent-almanac/skills/<skill-name> ~/.claude/skills/<skill-name>

Got: ls -la .claude/skills/<skill-name>/SKILL.md resolves to skill file.

If fail: Verify relative path right. From .claude/skills/, path ../../skills/<skill-name> should reach skill directory. Use readlink -f to debug symlink resolution. Claude Code expects flat structure at .claude/skills/<name>/SKILL.md.

Step 14: Scaffold Translations

Required for all skills. This step applies to both human authors and AI agents following this procedure. Do not skip — missing translations pile into stale backlog.

Scaffold translation files for all 4 supported locales right after committing new skill:

for locale in de zh-CN ja es; do
  npm run translate:scaffold -- skills <skill-name> "$locale"
done

Then translate scaffolded prose in each file (code blocks and IDs stay English). Finally regenerate status files:

npm run translation:status

Got: 4 files created at i18n/{de,zh-CN,ja,es}/skills/<skill-name>/SKILL.md, all with source_commit matching current HEAD. npm run validate:translations shows 0 stale warnings for new skill.

If fail: Scaffold fails? Verify skill exists in skills/_registry.yml before scaffolding — script reads registry. translation:status shows new files as stale? Check source_commit matches commit hash where English source was last modified.

Checks

• SKILL.md exists at skills/<skill-name>/SKILL.md
• YAML frontmatter parses without errors
• name field matches directory name
• description under 1024 characters
• All required sections present: When to Use, Inputs, Procedure, Validation, Common Pitfalls, Related Skills
• Every procedure step has concrete code and Expected/On failure pairs
• Related Skills reference valid skill names
• Skill listed in _registry.yml with right path
• total_skills count in registry updated
• SKILL.md ≤500 lines (extract to references/EXAMPLES.md if over)
• Estimated translation expansion acceptable (English source ≤~400 lines so translations stay <500)
• Citations added to references/CITATIONS.bib + CITATIONS.md if skill based on published methods
• Symlink exists at .claude/skills/<skill-name> pointing to skill directory
• Global symlink exists at ~/.claude/skills/<skill-name> (if globally available)

Pitfalls

• Vague procedures: "Configure the system appropriately" is useless to agent. Give exact commands, file paths, configuration values.
• Missing On failure: Every step that can fail needs recovery guidance. Agents can't improvise — they need fallback spelled out.
• Overly broad scope: Skill trying to cover "Set up entire development environment" should be 3-5 focused skills instead. One skill = one procedure.
• Untestable validation: "Code quality is good" can't be verified. "Linter passes with 0 warnings" can.
• Stale cross-references: When renaming or removing skills, grep for old name in all Related Skills sections.
• Description too long: Description field is what agents read to decide activation. Keep under 1024 characters. Front-load key info.
• Authoring at 500-line limit for single language: English skill at 490 lines will exceed 500 when translated to German (~10-20% expansion) or CJK languages. Target ~400 lines for English source. Use progressive disclosure (references/EXAMPLES.md) for rest.
• Avoid git mv on NTFS-mounted paths (WSL): On /mnt/ paths, git mv for directories can make broken permissions (d?????????). Use mkdir -p + copy files + git rm the old path instead. See environment guide troubleshooting section.

Examples

Well-structured skill follows this quality checklist:

1. Agent can decide whether to use it from description alone
2. Procedure can be followed mechanically without ambiguity
3. Every step has verifiable outcome
4. Failure modes have concrete recovery paths
5. Skill can be composed with related skills

Size reference from this library:

• Basic skills: ~80-120 lines (e.g., write-vignette, configure-git-repository)
• Intermediate skills: ~120-180 lines (e.g., write-testthat-tests, manage-renv-dependencies)
• Advanced skills: ~180-250 lines (e.g., submit-to-cran, setup-gxp-r-project)
• Skills with extended examples: SKILL.md ≤500 lines + references/EXAMPLES.md for large configs

See Also

• evolve-skill - evolve and refine skills created with this procedure
• create-agent - parallel procedure for creating agent definitions
• create-team - parallel procedure for creating team compositions
• write-claude-md - CLAUDE.md can reference skills for project-specific workflows
• configure-git-repository - skills should be version-controlled
• commit-changes - commit new skill and its symlinks
• security-audit-codebase - review skills for accidentally included secrets or credentials