create-skill

name	create-skill
description	Creates new Claude Code skills, auto-apply skills, or auto-trigger rules, or audits existing ones for quality and effectiveness.
argument-hint	<skill-name> [description] | audit [skill-name | all]

Skill Creator & Auditor

Two modes: Create a new skill or Audit an existing one.

Examples

• /create-skill wrds-fundamentals -- create a skill named wrds-fundamentals
• /create-skill event-study "Auto-apply skill for event study methodology" -- name + description
• /create-skill audit wrds-psql -- audit a specific skill
• /create-skill audit all -- audit all skills with summary table

Mode Selection

Parse $ARGUMENTS:

• audit, audit <name>, or audit all → Audit mode
• Everything else (name, description, or empty) → Create mode

---

CREATE MODE

Six phases: Determine Type → Gather Requirements → Choose Pattern → Generate → Validate → Register.

Phase 1: Determine Type

Parse $ARGUMENTS:

• First token = skill name (validate in Phase 2)
• Remaining tokens (if any) = optional description

If $ARGUMENTS is empty, use AskUserQuestion to ask:

"What do you want to create? Provide a name (lowercase, hyphens) and choose a type."

Three types with different file locations and frontmatter:

Type	Location	Key frontmatter
User-invocable skill (/name)	.claude/skills/{name}/SKILL.md	name, description, argument-hint
Auto-apply skill (triggers on task match)	.claude/skills/{name}/SKILL.md	name, description (includes "Auto-apply when...")
Auto-trigger rule (triggers on file paths)	.claude/rules/{name}.md	description, paths (globs). No name field.

How to decide (type):

• Does the user explicitly invoke it? → User-invocable skill
• Should it activate whenever Claude works on a matching task? → Auto-apply skill
• Should it activate whenever Claude edits files matching a glob pattern? → Auto-trigger rule

Skill vs Agent decision (ask this first):

Question	Yes →	No →
Is the workflow rigid with known inputs?	Skill	Consider agent
Does it need judgment, discovery, or error recovery?	Agent	Skill
Will it run frequently (>5x/week)?	Skill (token savings compound)	Either
Does it need its own tool set or isolation?	Agent	Skill

Skills run in the caller's context (zero spawn overhead, 75-80% fewer tokens than agents). If 90%+ of usage follows a fixed template, build a skill. Reserve agents for exploratory work. See docs/AGENT_LESSONS_LEARNED.md for case study.

Phase 2: Gather Requirements

Validate name

• Must match: ^[a-z][a-z0-9-]{0,63}$ (lowercase + hyphens, max 64 chars)
• Reject names containing "anthropic" or "claude" (reserved by Anthropic)
• Reject generic names: helper, utils, tools, misc, data, general, common, documents
• Collision check: if .claude/skills/{name}/ or .claude/rules/{name}.md already exists, ask user whether to overwrite or pick a new name
• If invalid, explain the rules with examples and re-ask

Collect requirements

Use a single AskUserQuestion to gather what's needed. Skip questions already answered by $ARGUMENTS:

1. Purpose (1-2 sentences): What does this skill do?
2. Trigger conditions: When should Claude activate this? (determines description field and rule globs)
3. Arguments: Does it take arguments? What format? (for argument-hint)
4. Auxiliary files needed? Reference docs, scripts, templates, style files?
5. Closest existing skill: Which skill in this project is most similar in structure?

If the user names an existing skill, read its SKILL.md to understand the pattern before proceeding.

Phase 3: Choose Structural Pattern

Read the exemplar SKILL.md file for each relevant pattern before generating.

Pattern catalog

Pattern	When to use	Exemplar (read this)
Phased workflow	Multi-step processes with dependencies between steps	new-project/SKILL.md (3 phases)
Checklist / decision table	Systematic validation, branching logic, audit	submission-prep/SKILL.md (10 categories)
Code template	Must produce or follow exact code patterns	wrds-psql/SKILL.md (pipeline template)
Gotchas / known issues	Encoding domain traps Claude must avoid	wrds-psql/SKILL.md (19 numbered items)
Reference table	Quick-lookup data (palettes, sizes, thresholds)	publication-figures/SKILL.md
Philosophy + principles	Judgment-heavy tasks needing guiding principles	build-deck/SKILL.md (Rhetoric of Decks)

Common combinations

Most skills combine 2-3 patterns:

• Phased workflow + code template: wrds-psql, onboard
• Checklist + reference table: submission-prep, style-check
• Philosophy + phased workflow: build-deck, respond-to-referee
• Gotchas + reference table: panel-data-rules, wrds-psql

Degrees of freedom

Match specificity to the task's fragility:

• Low freedom (exact scripts/templates): Fragile tasks where errors are costly. Write exact code blocks, step-by-step commands, no deviation. Example: wrds-psql pipeline.
• Medium freedom (checklists, decision tables): Stable structure, variable content. Write rules with room for judgment. Example: submission-prep checks.
• High freedom (principles, examples): Creative or judgment-heavy tasks. Write guiding principles and exemplars, let Claude adapt. Example: write-section, respond-to-referee.

Before generating, read 1-2 exemplar SKILL.md files for the chosen pattern(s). This grounds the output in proven patterns from this project.

Phase 4: Generate the Skill

Frontmatter

For user-invocable or auto-apply skills:

---
name: {validated-name}
description: "{third-person description stating WHAT and WHEN, max 1024 chars}"
argument-hint: "{format hint, only if skill takes arguments}"
---

For auto-trigger rules:

---
description: {third-person description of what the rule enforces}
paths:
  - "**/*.{ext}"
  - "{other glob patterns}"
---

Rules have NO name field. The paths field lists glob patterns that trigger the rule.

Description writing rules

• Third person: "Analyzes code for..." not "Analyze code for..."
• State WHAT + WHEN: "Extract text from PDFs. Use when working with PDF files or document extraction."
• Auto-apply skills: Description must include "Auto-apply when..." trigger clause
• Include trigger phrases users would actually say
• Add negative triggers if needed: "Do NOT use for simple X (use Y instead)."
• Max 1024 characters, no XML angle brackets (< >)
• Debug test: If someone asks Claude "when would you use {name}?", the description alone should give a clear answer

Body structure

# {Human-Readable Skill Name}

{1-2 sentence purpose statement}

## Examples                          ← only for user-invocable skills
- `/skill-name` -- basic usage
- `/skill-name arg` -- with argument
- `/skill-name --flag` -- variant

{Body sections using chosen pattern(s)}

## Output                           ← if skill produces a report/summary
{Template of what Claude prints when done}

Body writing rules

• Under 500 lines total. If approaching this, split reference content into auxiliary files.
• Challenge every paragraph: "Does Claude already know this? Does this justify its token cost?"
• Assume Claude knows programming, standard tools, common patterns. Only add what's genuinely new: domain rules, project conventions, gotchas, non-obvious sequences.
• Use forward slashes in all paths (never Windows backslashes).
• Provide defaults, not menus. If there are multiple valid approaches, pick one and note alternatives briefly.
• No magic numbers in code blocks — document every value with justification.
• Auto-apply enforcement: If the skill has auto-apply behavior, also add a backup rule in .claude/rules/workflow.md (or similar). Auto-apply triggers depend on the LLM noticing the description — rules are guarantees. Critical workflows need both.

Auxiliary files

Only create auxiliary files if:

1. The body would exceed ~400 lines without splitting
2. The content is reference data (lookup tables, code libraries) not core workflow
3. The file can stand alone without needing SKILL.md context

Keep references ONE level deep from SKILL.md. Never chain: file A → file B → file C.

For reference files longer than 100 lines, include a table of contents at the top.

Phase 5: Validate

Read best-practices.md (in this skill's directory) and run the validation checklist against the generated skill.

Frontmatter checks

• name matches ^[a-z][a-z0-9-]{0,63}$ (skills) or is absent (rules)
• description under 1024 chars
• description contains no XML tags (< >)
• description is in third person
• description states both WHAT and WHEN
• No "anthropic" or "claude" in name
• For auto-apply: description includes "Auto-apply when..." clause
• For rules: paths field present with valid glob patterns

Body checks

• Total line count under 500
• No Windows-style paths
• No tool/package assumptions without checking availability
• No menus of options without a default
• Every paragraph earns its token cost
• ## Examples section present (if user-invocable)
• ## Output section present (if skill produces reports)

Anti-pattern checks

• No deeply nested references (max 1 level from SKILL.md)
• No generic naming (helper, utils, misc, etc.)
• No verbose explanations of things Claude already knows
• No time-sensitive information without deprecation markers

Fix any violations before presenting the skill to the user.

Phase 6: Register

Update CLAUDE.md

1. Read root CLAUDE.md and find the ## Skills & Rules section
2. Determine the correct category subsection:
   • ### Factor Construction & Data — domain skills for PyBondLab
   • ### Infrastructure — meta-skills for creating/auditing skills, rules, agents
3. If no category fits, add to the nearest one or propose a new ### Category section
4. Add a line using the exact format (note: em-dash —, not --):
   • User-invocable: - \/skill-name` — One-line description`
   • Auto-apply: - \skill-name` — One-line description. Auto-apply when...`
   • Rule: - \rule-name` — One-line description`

Update README.md (infrastructure skills only)

Only add to the README skills tree if the skill is infrastructure-level (not domain-specific). Add under the skills/ section:

    {name}/SKILL.md                    # Short description (/skill-name)

Print summary

SKILL CREATED: {name}
==================

Type: {user-invocable skill | auto-apply skill | auto-trigger rule}
Location: {file path}
Patterns: {chosen patterns}
Lines: {line count} / 500

Registered in CLAUDE.md under: {category}

Files created:
  {list of files with line counts}

To test: ask Claude "when would you use {name}?" — the description should give a clear answer.

---

AUDIT MODE

Four phases: Read → Analyze → Report → Fix.

Phase 1: Read

Parse the audit target from $ARGUMENTS:

• audit <name> → read .claude/skills/{name}/SKILL.md
• audit all → list and read all SKILL.md files in .claude/skills/*/
• audit (no target) → list all skills as a numbered list, ask which to audit (or offer all)

Also read:

• best-practices.md (in this skill's directory) for evaluation criteria
• Root CLAUDE.md to check ecosystem registration

Phase 2: Analyze

Run 12 checks grouped in 4 categories. For each: PASS, WARN, or FAIL.

A. Frontmatter Quality

A1. Name Valid

• PASS: name present, matches ^[a-z][a-z0-9-]{0,63}$, no reserved words ("anthropic", "claude"), not generic
• WARN: Name valid but generic (e.g., helper, data, utils)
• FAIL: Missing name, invalid characters, or contains reserved words

A2. Description Present

• PASS: description present, non-empty, under 1024 characters, no XML angle brackets
• WARN: Present but under 50 characters (likely too vague for routing)
• FAIL: Missing or empty

A3. Description Quality

• PASS: Third person, states both WHAT and WHEN
• WARN: First person, or missing WHEN clause
• FAIL: Neither WHAT nor WHEN stated

A4. Type-Specific Fields

• PASS: Auto-apply has "Auto-apply when..." clause; user-invocable with args has argument-hint; rules have paths
• WARN: Field present but imprecise (vague argument-hint, overly broad paths)
• FAIL: Required field missing for the skill's type

B. Body Quality

B5. Line Count

• PASS: Under 400 lines
• WARN: 400-500 lines (approaching limit)
• FAIL: Over 500 lines (suggest splitting into auxiliary files)

B6. Structured Sections

• PASS: Clear headers, organized by pattern (phased workflow, checklist, etc.)
• WARN: Missing 1-2 expected sections
• FAIL: Unstructured wall of text or only 1 section

B7. Examples Section

• PASS: ## Examples present with usage patterns (user-invocable) or N/A (auto-apply/rules)
• WARN: Examples present but incomplete (missing argument variants)
• FAIL: Missing for a user-invocable skill

B8. Token Efficiency

• PASS: No verbose fundamentals Claude already knows; every paragraph earns its cost
• WARN: 1-2 sections could be trimmed
• FAIL: Substantial filler content

B9. Anti-Patterns

Check for: Windows-style backslash paths, menus without defaults, nested references deeper than 1 level, tool/package assumptions without availability checks.

• PASS: None found
• WARN: 1-2 minor instances
• FAIL: Systemic anti-pattern usage

C. Ecosystem Integration

C10. CLAUDE.md Registration

Check root CLAUDE.md for the skill under the Skills & Rules section.

• PASS: Listed in correct category with matching description
• WARN: Listed but description or category doesn't match
• FAIL: Not listed at all

C11. Auxiliary Files

Check if body references other files (e.g., best-practices.md, templates).

• PASS: All referenced files exist; max 1 level deep from SKILL.md
• WARN: Referenced file exists but appears unused by the skill body
• FAIL: Referenced file missing, or chain references (A → B → C)
• N/A: No auxiliary files referenced (mark as PASS)

D. Cross-Skill Consistency

D12. No Scope Overlap

Compare this skill's description against all other skills.

• PASS: No substantial overlap with other skills' descriptions
• WARN: Minor wording overlap (different skills, similar phrasing)
• FAIL: Another skill covers the same domain (creates routing ambiguity)

Phase 3: Report

Print structured report:

SKILL AUDIT: {name}
=============================
File: .claude/skills/{name}/SKILL.md | Lines: {count} | Type: {user-invocable|auto-apply|rule}

A. FRONTMATTER          B. BODY QUALITY
[PASS] A1 Name          [PASS] B5  Lines ({n})
[PASS] A2 Description   [PASS] B6  Sections
[PASS] A3 Desc quality  [PASS] B7  Examples
[PASS] A4 Type fields   [PASS] B8  Token efficiency
                         [PASS] B9  Anti-patterns

C. ECOSYSTEM            D. CONSISTENCY
[PASS] C10 CLAUDE.md    [PASS] D12 Overlap
[PASS] C11 Aux files

SUGGESTIONS:
1. [B5] At 478 lines, approaching the 500-line limit.

RESULT: 12/12 passed, 0 warnings, 0 failures

For all mode, print each skill's report separately, then a summary table:

SUMMARY: {N} skills audited
==============================
| Skill                  | Pass | Warn | Fail |
|------------------------|------|------|------|
| build-deck             |  12  |   0  |   0  |
| create-skill           |  11  |   1  |   0  |
| wrds-psql              |  12  |   0  |   0  |
| ...                    |      |      |      |

Phase 4: Fix (Optional)

After reporting, offer to fix FAIL items:

• "Would you like me to fix the {N} FAIL items? I'll show each proposed change before applying."
• C10 (CLAUDE.md): propose adding skill to correct category
• A3 (description): propose rewritten description in third person with WHAT+WHEN
• B7 (examples): propose ## Examples section with usage patterns
• Other items: describe the fix, get approval, apply

Never auto-fix without showing the proposed change first.

---

Communication Rules

• Before Phase 1 (either mode), print: Reading best practices reference...
• In Create mode, always show the draft before writing
• In Audit mode, if auditing multiple skills, print each report separately, then a summary table
• If a newly created skill fails its own audit, fix it before considering the skill complete
• Use the compact report format above — avoid walls of prose