Skeall Skill Builder

Agent Skills (SKILL.md) builder, auditor, and improver for cross-platform LLM agents. Use for "skeall", "build a skill", "create skill", "improve skill", "audit skill", "skill review", or any SKILL.md question. Follows agentskills.io standard.

Skeall

Create, improve, and audit Agent Skills following the Agent Skills open standard. This skill encodes lessons from real-world skill development and cross-platform compatibility testing.

Quick start

text

/skeall --create              # Interview, then scaffold new skill
/skeall --improve <path>      # Analyze and improve existing skill
/skeall --scan <path>         # Audit only, no changes (report)
/skeall --scan .              # Audit skill in current directory
/skeall --scan-all            # Batch scan all skills in ~/.claude/skills/
/skeall --scan-all <dir>      # Batch scan all skills in custom directory
/skeall --healthcheck <path>  # Runtime check single skill (orphans, deps, env, URLs)
/skeall --healthcheck-all     # Runtime check all skills in ~/.openclaw/skills/
/skeall --healthcheck-all <dir> # Runtime check all skills in custom directory

---

Mode 1: Create (scaffold a new skill)

Process

1. Interview the user (ask questions 1-4 always, then 5-6 if user hasn't already specified complexity or distribution scope):

   • What does this skill do? (one sentence)
   • What category? Reference / Task / MCP Enhancement / Hybrid. See references/advanced-patterns.md
   • What triggers should activate it? (keywords users would type)
   • Does it accept arguments? (e.g., file path, topic — use $ARGUMENTS or $ARGUMENTS[N] in body)
   • How complex is it? (single file vs references/ needed)
   • Will this skill be shared? (personal / project / public) — affects README, license, metadata

2. Generate the skill structure:

text

{skill-name}/
├── SKILL.md                    # Core instructions (always loaded)
├── references/                 # On-demand detail files
│   ├── {topic-1}.md
│   └── {topic-2}.md
└── README.md                   # GitHub-facing (optional)

3. Write SKILL.md following these rules:

   • YAML frontmatter with name and description (see Frontmatter section)
   • Body under 500 lines, under 5000 tokens
   • Instruction-based framing, not persona-based
   • Progressive disclosure: core in SKILL.md, details in references/

4. Show the generated SKILL.md to user for review.

5. Run --scan on the generated skill. If any HIGH issues found, fix them before delivering.

Next step: "Optimize with reprompter?" (optional, see Reprompter section). Then suggest installing the skill.

---

Mode 2: Improve (refactor existing skill)

Process

1. Read SKILL.md first. Read reference files only if scan identifies issues requiring them (broken links, routing table mismatches).
2. Run the scan checklist (see Mode 3).
3. For each issue found, propose a specific before/after edit.
4. Group edits by priority: HIGH first, then MEDIUM, then LOW.
5. Ask user: "Fix all? Review one by one? Or just the HIGHs?" (recommended: fix all HIGHs automatically, review MEDIUMs)
6. Apply approved edits.
7. Re-scan once. If new issues appear, report them but do not enter an infinite fix loop.

Next step: "Run --scan to verify?" or "Commit changes?"

Common improvements

Problem	Fix
Body over 5000 tokens	Move detail sections to references/
Redundant content	Single source of truth, reference elsewhere
Persona-based framing	Switch to instruction-based framing
Missing trigger phrases	Add keywords to description field
Platform-specific patterns	Replace with universal formatting
No progressive disclosure	Add routing table to reference files

---

Mode 3: Scan (audit and report)

Process

1. Read the skill's SKILL.md and directory structure.
2. Check every item in the checklist below.
3. Output a severity-tagged report.

Report format

text

## Skill Audit: {skill-name}

Score: X.X/10

STRUCTURE
  [PASS] S1 -- SKILL.md exists at root
  [FAIL] S3 HIGH -- name does not match directory name
  [WARN] S5 MEDIUM -- No references/ directory

FRONTMATTER
  [PASS] F2 -- Trigger phrases present
  [FAIL] F1 HIGH -- description over 1024 characters

CONTENT
  [WARN] C5 MEDIUM -- Persona-based framing ("You are an expert")
  [FAIL] C3 HIGH -- Same content repeated 3 times (lines 45, 120, 280)

LLM-FRIENDLINESS
  [WARN] L4 MEDIUM -- Unicode arrows instead of markdown tables
  [PASS] L3 -- No emoji markers in headings

SECURITY
  [PASS] SEC1 -- No XML angle brackets in frontmatter
  [PASS] SEC3 -- No hardcoded secrets

CROSS-PLATFORM
  [PASS] X1 -- No {baseDir} placeholders
  [WARN] X4 LOW -- No multi-platform install instructions in README

Total: 3 HIGH | 4 MEDIUM | 1 LOW

Next step after scan: "Want me to fix these? Run /skeall --improve <path>"

Error handling

Input	Response
No SKILL.md found at path	"No skill found at {path}. Did you mean --create?"
Empty directory for --scan-all	"No skills found in {dir}. Skills must have a SKILL.md file."
Invalid YAML frontmatter	Report the parse error, suggest fixing frontmatter first
--improve on non-skill file	"Not a valid skill (no YAML frontmatter). Try --create instead."
--improve on a skill scoring 10/10	"Scan found 0 issues (score 10.0/10). No changes needed. Consider running trigger and functional tests."

---

Agent Skills spec reference

Frontmatter (required)

yaml

---
name: my-skill-name
description: What this skill does and when to use it. Include trigger phrases.
---

name rules:

• Must match the parent directory name
• Lowercase alphanumeric with hyphens only (unicode lowercase allowed)
• 1-64 characters, no leading/trailing/consecutive hyphens
• No spaces, no special characters, no reserved words ("anthropic", "claude")
• Recommended: gerund form (processing-pdfs, testing-code) or descriptive noun (pdf-processor)

description rules:

• Explain WHAT it does AND WHEN to use it
• Write in third person ("Processes files", not "I can process" or "You can use")
• Include trigger phrases users would actually type
• Put the most important keyword first (platforms weight first words)
• Spec limit: 1024 characters. Recommended: under 300 for best matching
• Use noun-phrase style ("Guide for X"), not persona style ("Expert in X")
• No XML angle brackets (<, >) in any frontmatter value (injection risk)

Optional frontmatter fields

These are silently ignored by platforms that do not support them:

yaml

license: MIT                          # For distributed skills
compatibility: "Node.js 18+"         # Environment requirements (max 500 chars)
metadata:                             # Arbitrary key-value (author, version)
  author: your-name
  version: 1.0.0
allowed-tools: "Bash Read"           # Experimental: space-delimited tool list
user-invocable: true                  # Show in /slash menu (false = hidden but still callable)
disable-model-invocation: true        # Block Claude from auto-loading this skill
argument-hint: "<file-path>"          # Hint shown in /skill autocomplete
model: opus                           # Override model for this skill
context: fork                         # Run in isolated subagent
agent: general-purpose                # Subagent type: general-purpose, Explore, Plan, or custom
hooks:                                # Skill-scoped lifecycle hooks
  PostToolCall: "validate.sh"

Directory structure

text

skill-name/
├── SKILL.md           # REQUIRED -- core instructions
├── references/        # OPTIONAL -- on-demand detail files
├── scripts/           # OPTIONAL -- executable scripts
├── assets/            # OPTIONAL -- static assets (images, etc.)
└── README.md          # OPTIONAL -- GitHub-facing docs

Token budget

Level	Content	Budget
Metadata (YAML frontmatter)	name + description	~100 tokens
Instructions (SKILL.md body)	Always loaded by LLM	< 5000 tokens
References (each file)	Loaded on demand	~2000-3000 tokens each

Estimation: ~1.5 tokens per word for mixed code+prose markdown.

Progressive disclosure: SKILL.md body should handle ~70% of user requests. Reference files handle the remaining 30% (detailed workflows, complete examples, edge cases).

Line limits

Guideline	Limit
SKILL.md body	Under 500 lines (under 300 for complex skills with many references)
Reference files	No hard limit, but keep each under 700 lines. Add TOC at top if over 100 lines

---

Scan checklist

Structure checks

ID	Severity	Check
S1	HIGH	SKILL.md exists at skill root
S2	HIGH	YAML frontmatter present with --- delimiters
S3	HIGH	name field present and valid (lowercase, hyphens, 1-64 chars, no consecutive hyphens)
S4	HIGH	description field present
S5	MEDIUM	References in references/ not loose at root
S6	LOW	README.md present for GitHub-hosted skills
S7	LOW	No unnecessary files (node_modules, .DS_Store, etc.)
S8	HIGH	name field matches parent directory name

Frontmatter checks

ID	Severity	Check
F1	HIGH	Description under 1024 characters (spec limit)
F1b	LOW	Description under 300 characters (recommended for matching)
F2	HIGH	Description includes trigger phrases
F3	MEDIUM	Description starts with noun phrase, not "Expert in"
F4	MEDIUM	Name 1-64 characters, no leading/trailing/consecutive hyphens
F5	LOW	No platform-specific fields (keeps universal compatibility)

Content checks

ID	Severity	Check
C1	HIGH	Body under 500 lines
C2	HIGH	Estimated tokens under 5000
C3	HIGH	No content repeated in SKILL.md body (controlled repetition across reference files is acceptable)
C4	HIGH	Code examples use correct, verified patterns
C5	MEDIUM	Instruction-based framing (not "You are an expert")
C6	MEDIUM	Has routing table to reference files (if references/ exists)
C7	MEDIUM	Troubleshooting section present (for skills with code blocks or CLI commands)
C8	LOW	No deprecated content at the top (wastes prime token space)
C9	MEDIUM	Routing table completeness: if references/ exists, SKILL.md lists ALL files in references/
C10	MEDIUM	Internal count consistency: claimed counts ("34 patterns", "8 phases") match actual content
C11	MEDIUM	No stale references: documented APIs, functions, model names exist in actual source

LLM-friendliness checks

ID	Severity	Check
L1	HIGH	Tables for structured data (not bullet lists with arrows)
L2	HIGH	Imperative instructions ("Do X", not "You should consider X")
L3	MEDIUM	No emoji in headings or structural markers (frontmatter metadata values are data, not markers)
L4	MEDIUM	No Unicode arrows or special characters for data flow
L5	MEDIUM	Consistent heading hierarchy (no skipped levels). Ignore headings inside fenced code blocks
L6	MEDIUM	Code blocks have language tags
L7	LOW	Sentence case headings (not Title Case)
L8	LOW	No nested blockquotes (some LLMs parse poorly)

Security checks

ID	Severity	Check
SEC1	HIGH	No XML angle brackets (<, >) in frontmatter values
SEC2	HIGH	Name does not contain reserved words ("anthropic", "claude")
SEC3	HIGH	No hardcoded API keys, tokens, or secrets in any skill file
SEC4	MEDIUM	Scripts include error handling (not bare commands)
SEC5	HIGH	No credential patterns (Bearer eyJ, sk-/pk- prefixes, api_key=/token= + long strings). Ignore $ENV_VAR refs and YOUR_KEY_HERE placeholders

Cross-platform checks

ID	Severity	Check
X1	HIGH	No {baseDir} placeholders (breaks non-OpenClaw platforms)
X2	MEDIUM	Relative paths from SKILL.md to references/
X3	MEDIUM	Internal links use standard markdown [text](path)
X4	LOW	README has multi-platform install paths

Runtime checks (healthcheck mode only)

ID	Severity	Check
R1	HIGH	Orphan skill: not referenced in any config or skill registry
R2	HIGH	Duplicate name: same name field found in 2+ skill directories
R3	HIGH	Trigger collision: description phrases 80%+ overlap with another skill
R4	HIGH	Broken dependency: file referenced in SKILL.md does not exist
R5	MEDIUM	Stale endpoint: URL in curl command returns 404 or times out
R6	MEDIUM	Missing env var: $VAR reference found but not set in environment
R7	LOW	Token cost: estimated tokens loaded per session

LLM-friendliness patterns

These patterns come from real cross-platform testing. Apply them when creating or improving skills.

Do

• Tables over prose for structured data (parameters, options, comparisons)
• Single source of truth for any concept explained more than once
• Instruction-based framing: "This skill provides instructions for X. Follow these patterns exactly."
• Imperative verbs: "Call X after Y", "Use Z for W"
• Compact routing table at the top pointing to reference files
• Parameter comments inline in code blocks: providerAddress, // 1st: wallet address
• Copyable progress checklists for multi-step workflows (LLM tracks completion)
• Validation feedback loops for quality-sensitive output (generate, score, retry if needed)
• Consistent freedom level per section — do not mix exact scripts with vague guidance. See references/advanced-patterns.md

Do not

• Persona-based framing: "You are an expert in..." (Claude-leaning, other LLMs respond better to instructions)
• Emoji markers in headings or structural elements (token-expensive, parsed inconsistently). Emoji in frontmatter metadata values is data and acceptable
• Unicode arrows (→, ←) for data flow — use tables or plain prose
• Blockquote warnings at top of SKILL.md (wastes prime token space, primes distrust)
• "When Users Ask" checklists with 10+ items (bury critical rules, use tables instead)
• Synonym cycling for the same concept (confuses LLMs about whether it's the same thing)
• Repeated content (wastes tokens, risks contradictions if copies drift)
• Assuming exclusive activation (other skills may load simultaneously — declare dependencies explicitly)

Description field optimization

Good description pattern:

text

{Product/Tool name} guide for {primary use case}. Covers {feature list}.
Use this skill for {trigger phrases separated by commas}.

Example:

yaml

description: 0G Compute Network guide for decentralized AI inference and fine-tuning.
  Covers chatbots, image generation, speech-to-text, SDK integration, CLI commands.
  Use this skill for any 0G compute, 0G AI, or decentralized GPU question.

---

Cross-platform compatibility

Universal format (works everywhere)

Only name and description in frontmatter. Standard markdown body. Relative paths. No platform-specific syntax.

Platform discovery paths

Platform	User-wide	Project
Claude Code	~/.claude/skills/{name}/	.claude/skills/{name}/
OpenAI Codex	~/.agents/skills/{name}/	.agents/skills/{name}/
OpenClaw	~/.openclaw/skills/{name}/	.openclaw/skills/{name}/
Cursor	Standard SKILL.md discovery	Project skills dir
Gemini CLI	Standard SKILL.md discovery	Project skills dir

Codex-specific extensions

OpenAI Codex adds an optional openai.yaml file alongside SKILL.md for platform metadata (interface, policy, dependencies). SKILL.md itself stays cross-platform. See references/advanced-patterns.md for details.

Things that break cross-platform

Pattern	Problem	Fix
{baseDir} placeholder	Only OpenClaw resolves it	Use relative paths
Platform-specific instructions	Confuse other LLMs	Keep instructions generic
Hardcoded paths	Break on other OS/platforms	Use relative from SKILL.md

Token estimation

Estimate: wc -w SKILL.md × 1.5 (prose) or × 1.7 (code-heavy files).

Budget allocation guide

Skill complexity	SKILL.md target	References needed?
Simple (one topic, few commands)	100-200 lines / ~1500 tokens	No
Medium (multiple features, some code)	200-350 lines / ~3000 tokens	1-2 files
Complex (multi-domain, many patterns)	300-450 lines / ~4500 tokens	3-5 files

Severity reference

Severity	Meaning	Action
HIGH	Breaks spec compliance or causes LLM confusion	Must fix
MEDIUM	Reduces quality or cross-platform compatibility	Should fix
LOW	Minor improvement opportunity	Fix if time permits

---

Mode 4: Batch scan (scan-all)

Scan every skill in a directory at once. Useful for auditing your entire skill collection.

Process

1. List all subdirectories containing SKILL.md in the target path (default: ~/.claude/skills/).
2. Run Mode 3 (scan) on each skill. Output each skill's score as you complete it.
3. Output a summary table sorted by score ascending (worst first).

Report format

text

## Batch Skill Audit

| Skill | Score | HIGH | MEDIUM | LOW | Status |
|-------|-------|------|--------|-----|--------|
| seo-optimizer | 5/10 | 3 | 2 | 1 | NEEDS WORK |
| reprompter | 6/10 | 2 | 3 | 0 | NEEDS WORK |
| blogger | 7/10 | 1 | 1 | 2 | NEEDS WORK |
| humanizer-enhanced | 8/10 | 0 | 2 | 1 | PASS |

Total: 4 skills scanned
PASS: 1 | NEEDS WORK: 3

Top issues across all skills:
1. [HIGH] C2 reprompter: Body exceeds 5000 tokens (est. 8,200)
2. [HIGH] C3 seo-optimizer: Content repeated 4 times
3. [HIGH] C5 reprompter: Persona-based framing

PASS threshold: Score 7+ with zero HIGH issues.

Next step: "Start with the lowest-scoring skill. Run /skeall --improve <path> on it."

---

Mode 5: Health check (runtime audit)

Checks whether a skill actually works at runtime — beyond what static scan can catch. Run static scan (Mode 3) first and fix HIGH issues before health check.

Process

1. Run R1-R7 checks against the target skill.
2. For --healthcheck-all: cross-check all skills for duplicates (R2) and trigger collisions (R3).
3. Output severity-tagged report with sections: RUNTIME, DUPLICATES, TRIGGER COLLISIONS.
4. Labels: [FAIL] for HIGH issues (must fix), [WARN] for MEDIUM (runtime risk), [INFO] for LOW.

For detection algorithms, report format examples, and batch output format, see references/healthcheck.md.

---

Scoring methodology

Formula: Score = max(0, 10 - (HIGHs x 1.5) - min(MEDIUMs x 0.5, 3) - min(LOWs x 0.2, 1))

PASS threshold: Score 7+ AND zero HIGH issues. For detailed examples, see references/scoring.md.

---

Troubleshooting

Issue	Fix
Token estimate seems wrong	Use wc -w and multiply by 1.5 (prose) or 1.7 (code-heavy)
Scan reports FAIL but skill works fine	HIGHs indicate spec/LLM issues, not runtime bugs. Fix them anyway.
Batch scan misses a skill	Skill directory must contain SKILL.md at root
Two fixes contradict each other	Flag the conflict, ask user to choose (e.g., "shorten file" vs "add section")
Score 7+ but still NEEDS WORK	Check for HIGH issues. Any HIGH = NEEDS WORK regardless of score

---

References

For detailed checklists and examples, see:

• Anti-patterns with before/after examples
• Runtime health check algorithms and real examples
• Complete SKILL.md template
• Scoring methodology details
• Testing patterns and examples
• Advanced patterns: categories, freedom levels, distribution, MCP, workflows

Testing your skill: After create or improve, test trigger activation (3-5 keyword variants), functional output, and negative (unrelated queries stay quiet). See references/testing.md.

MCP integration: Use fully qualified tool names (mcp__server__tool_name). Document required MCP servers and provide fallbacks. See references/advanced-patterns.md.

Reprompter integration (optional): After --create interview, say "reprompter optimize" to score description variants and validate code examples. Works standalone if reprompter is not installed.