skill-forge

Skill Forge

Unified skill development toolkit. Supersedes skill-creator — combines its creation process with quality validation, description optimization, and testing.

Iron Law: Skills must be discovered to be useful. The description is everything.

When to Use

• Before writing or editing any SKILL.md file
• When creating a new skill from scratch
• When improving an existing skill's discovery rate
• When validating skill quality before deployment
• When scanning a skill/repo before sharing publicly

Boundaries

• One-off instructions belong in CLAUDE.md, not a skill
• Simple tool usage Claude already knows
• Tasks that don't repeat across sessions

Why This Skill Exists

Even when the task seems simple, forge adds value you can't get from training alone:

• CSO scoring catches description patterns that look fine but won't trigger discovery
• Register checks ensure skills create a calm, productive emotional baseline
• Lint validation catches structural issues (naming, frontmatter, section depth) before they cause silent failures
• Small description edits are exactly where CSO scoring matters most — a word change can shift discovery rates

Quick Start

# 1. Initialize new skill
scripts/init_skill.py my-skill --path ~/.claude/skills

# 2. Edit SKILL.md (see Workflow below)

# 3. Lint for structure issues
${CLAUDE_SKILL_DIR}/scripts/lint_skill.py /path/to/skill

# 4. Score description quality (CSO)
${CLAUDE_SKILL_DIR}/scripts/score_description.py /path/to/skill

# 5. Test with subagent (optional but recommended)
${CLAUDE_SKILL_DIR}/scripts/test_skill.py /path/to/skill

# 6. Package for distribution (optional)
${CLAUDE_SKILL_DIR}/scripts/package_skill.py /path/to/skill

Workflow: 6-Step Process

Step 1: Understand with Concrete Examples

Goal: Know exactly how the skill will be used before building.

Questions to answer:

• "What would a user say that should trigger this skill?"
• "Can you give examples of how this skill would be used?"
• "What should happen after the skill triggers?"

Exit criterion: Clear list of trigger phrases and expected behaviors.

Step 2: Plan Reusable Contents

Analyze each example to identify:

Content Type	When to Include	Example
scripts/	Same code rewritten repeatedly	rotate_pdf.py
references/	Documentation Claude should reference	schema.md
assets/	Files used in output (not loaded)	template.pptx

Exit criterion: List of scripts/references/assets to create.

Step 3: Initialize

scripts/init_skill.py <skill-name> --path <directory>

Creates SKILL.md template, example scripts/references/assets. Delete unneeded files.

Step 4: Edit

Order matters:

1. Create scripts/references/assets first
2. Test scripts actually work
3. Write SKILL.md last (it references the resources)

SKILL.md Structure

---
name: kebab-case-name
description: [See CSO Patterns below]
---

Body sections:

• Core principle / Iron Law
• When to Use / When NOT to Use
• Workflow with success criteria
• Anti-patterns
• Quick reference
• Integration with other skills

Naming

• Lowercase letters, numbers, hyphens only. Max 64 chars.
• Must match directory name exactly.
• Gerund or capability form preferred.

Good	Bad	Why
systematic-debugging	debug	Verb, not capability
workspace-fluency	utils	Generic, no information
test-driven-development	pdf-helper	"helper" is meaningless
desired-outcomes	my-skill	Doesn't describe purpose

CSO Patterns

The description determines discovery. Pattern: [ACTION VERB] + [LIFECYCLE CONTEXT] + [METHOD/VALUE PREVIEW]

Best: Clear lifecycle positioning with specific context

description: Orchestrates skill development — required before writing or editing any SKILL.md file. Unified 6-step workflow with automated validation, CSO scoring, and subagent testing.

Why: third-person verb, "required before" positioning, specific context ("any SKILL.md file"), method preview.

Good: Specific trigger with method preview

description: Guides systematic debugging before proposing fixes. 4-phase framework (root cause, pattern analysis, hypothesis testing, implementation) ensures understanding before solutions. Triggers on 'test failing', 'unexpected behavior', 'debug this'.

Why: specific trigger + lifecycle positioning + method preview + value statement.

Good: Natural phrase triggers

description: Coaches on outcome quality. Triggers on 'check my outcomes', 'is this a good outcome', 'review my Todoist' when discussing strategic work.

Why: explicit phrases in quotes, context qualifier.

Good: Scope boundaries to prevent over-triggering

description: Advanced data analysis for CSV files — statistical modelling, regression, clustering. For simple data exploration, use data-viz skill instead.

Why: clear scope boundary in description steers Claude before body loads.

When to add scope boundaries:

• Skill overlaps with another skill's domain
• Skill triggers on common words that appear in unrelated requests
• Users report the skill loading when it shouldn't

Patterns to improve:

Pattern	Problem	Better
"Helps with..."	Vague, no trigger	Specific phrases in quotes
"Use when creating..."	Too generic	"Required before..." or "Orchestrates..."
No timing condition	Claude treats invocation as optional	Add lifecycle positioning: "before", "first"
Generic actions	Claude "knows" without loading	Domain-specific phrases
Command doesn't name skill	Skill not discoverable	"Invoke the name skill"
Over-triggers on related topics	Loads when it shouldn't	Add scope boundary in description

Run scripts/score_description.py to validate. See references/cso-guide.md for full guidance.

Step 5: Validate

# Automated lint (structure, naming, frontmatter)
scripts/lint_skill.py <skill-path>

# CSO score (description quality)
scripts/score_description.py <skill-path>

# Subagent test (discovery + workflow)
scripts/test_skill.py <skill-path>

All checks should pass before Step 6.

Step 6: Package (Optional)

scripts/package_skill.py <skill-path> [output-dir]

Creates .skill file (zip format) for distribution.

Quality Checklist

Structure

• SKILL.md under 500 lines
• Name matches directory exactly (kebab-case)
• Name is gerund/capability form
• Description is third-person ("Orchestrates", not "Use")
• Description includes trigger AND method AND timing
• Description ends with (user) tag for user-defined skills
• References one level deep from SKILL.md
• YAML frontmatter has name and description only

Content

• No time-sensitive information
• Consistent terminology throughout
• Concrete examples, not abstract rules
• Configuration values justified
• Error handling documented
• Dependencies explicitly listed
• Anti-patterns section present

Workflow

• Clear phases/steps with success criteria
• When to Use AND When NOT to Use sections
• Integration points with other skills explicit
• Verification/validation included
• Quick reference for common operations

Discovery

• Lifecycle positioning (before/first/required) used appropriately
• Trigger phrases are natural language in quotes
• Context qualifiers included (when appropriate)
• Method preview gives Claude enough to decide relevance
• If paired with command, command names the skill explicitly
• Scope boundaries added if skill overlaps with others

Register

• Opens with what good work looks like, not what to avoid
• ALL CAPS used sparingly (abbreviations fine, emphatic caps minimal)
• Prohibitions balanced with positive specifications
• Constraints framed as craft standards, not threats

Skill Patterns

See references/skill-patterns.md for full taxonomy. Summary:

Type	Key Feature	Description Pattern
Process	Phases with gates	Lifecycle positioning (before/first)
Fluency	Tool best practices	Specific trigger phrases
Coaching	Quality criteria	Natural language triggers
Gate	Checklist validation	Required before...
Skill+CLI	Orchestrates CLI tool	Required before any cli command

Skill+CLI Pattern (Most Powerful)

When skill orchestrates a CLI tool. See references/skill-cli-pattern.md for full template.

# {skill-name}
Orchestrates {domain} using `{cli}` command.
## CLI Reference
## Workflows
## When Skill Extends CLI (coaching, quality criteria)
## Error Recovery

What High-Invocation Skills Share

1. Clear lifecycle positioning — "before", "first", "required"
2. Specific trigger phrases in quotes
3. Method preview that's actionable
4. Clear pitfall documentation that catches mistakes
5. Integration points that compose with other skills
6. Calm, craft-oriented register — constraints as quality standards

What Low-Invocation Skills Suffer From

1. Generic "Use when..." descriptions
2. Vague propositions ("helps with", "guides", "assists")
3. Missing lifecycle positioning
4. Documenting what Claude already knows

Common Mistakes

Discovery

Mistake	Symptom	Better
"Use when creating..."	Claude bypasses skill	"Required before..."
"Helps with..."	Skill never invoked	Specific trigger phrases
No lifecycle positioning	Claude treats invocation as optional	Add "before", "first", "required"
Generic actions	Claude "knows" without loading	Domain-specific phrases

Structure

Mistake	Symptom	Better
SKILL.md > 500 lines	Token bloat	Split into references/
Name doesn't match dir	Skill not found	Keep synchronized
Deeply nested refs	Discovery fails	One level deep max

Content

Mistake	Symptom	Better
Explaining known things	Wastes tokens	Domain-specific only
Magic constants	Unclear reasoning	Justify all values
Many options, no default	Analysis paralysis	Recommend one path
Heavy threat/urgency language	Corner-cutting, concealment	Frame constraints as craft standards

Quick Reference

Minimum Viable Skill

---
name: kebab-case-name
description: [ACTION VERB] + [LIFECYCLE CONTEXT] + [METHOD/VALUE]. Triggers on 'phrase1', 'phrase2'. (user)
---

# Skill Title

[What good work looks like — the core principle]

## When to Use
[Specific triggers with examples]

## Boundaries
[What this skill is not for]

## Workflow
[Steps with success criteria]

## Common Mistakes
[Pitfalls and better alternatives]

Files to Include

File	Purpose	When Required
SKILL.md	Core instructions	Always
references/*.md	Detailed guides	When SKILL.md > 500 lines
scripts/*.py	Utility scripts	When deterministic code needed
assets/*	Output templates	When Claude uses files in output

Before Sharing

Run the sharing scanner:

scripts/scan.py <skill-path>
scripts/scan.py --risk high <skill-path>  # High-risk only

Detects: emails, paths with usernames, secrets, company terms. See references/sharing-scan.md for triage guidelines.

Integration

Anthropic scripts (symlinked from skill-creator):

• init_skill.py — generate template
• package_skill.py — create .skill file

Forge scripts:

• lint_skill.py — automated structure validation
• score_description.py — CSO quality scoring
• test_skill.py — subagent pressure testing
• scan.py — PII/secrets scanner for sharing
• render_graphs.py — DOT workflow diagrams to SVG

References

• references/cso-guide.md — Claude Search Optimization principles
• references/skill-cli-pattern.md — Skill+CLI template
• references/skill-patterns.md — Pattern taxonomy with examples
• references/rationalization-table.md — Why this skill exists even when the task seems simple
• references/register-principles.md — Emotional register guidelines for instructional text
• references/sharing-scan.md — Sharing triage guidelines
• references/dot-graphs.md — DOT graph syntax for workflow diagrams