📚 Skill

A Skill is a reusable capability that provides specialized knowledge or methodology for specific task types.

Key Characteristics

Property	Value
Invocation	Skill tool or automatic based on context
Location	`.claude/skills/*/SKILL.md`
Loading	On-demand when relevant
Scope	Enhances 🐔 main agent capabilities

File Structure

bash

.claude/skills/test-driven-development/
└── SKILL.md

markdown

# .claude/skills/test-driven-development/SKILL.md

---
description: Use when implementing features - write tests first, then code
---

# Test-Driven Development Skill

## Methodology
1. RED: Write a failing test
2. GREEN: Write minimal code to pass
3. REFACTOR: Clean up while tests pass

Note: Skill name from directory name. Frontmatter: name (optional), description (required), allowed-tools (optional).

Frontmatter Reference

Field	Required	Description
`name`	No	Skill name (default: directory name, max 64 chars)
`description`	Yes	When to use this skill (max 1024 chars)
`allowed-tools`	No	Restricts tool access for this skill

Mermaid Representation

mermaid

%%{init: {'theme': 'base', 'themeVariables': {'lineColor': '#64748b'}}}%%
flowchart TB
    classDef user fill:#6366f1,stroke:#4f46e5,stroke-width:2px,color:#ffffff
    classDef main fill:#8b5cf6,stroke:#7c3aed,stroke-width:2px,color:#ffffff
    classDef skill fill:#8b5cf6,stroke:#7c3aed,stroke-width:2px,color:#ffffff
    classDef decision fill:#f59e0b,stroke:#d97706,stroke-width:2px,color:#ffffff

    REQ["🙋‍♀️📥 User Request"]:::user --> CHECK{"📚 Skill Applicable?"}:::decision
    CHECK -->|Yes| LOAD["📚 Load Skill"]:::skill
    CHECK -->|No| DIRECT["🐔⚡ Direct Execution"]:::main
    LOAD --> APPLY["🐔📚 Apply Methodology"]:::main
    APPLY --> EXEC["🐔⚡ Execute with Skill"]:::main
    EXEC --> RESULT["💁‍♀️📤 Enhanced Result"]
    DIRECT --> RESULT

How Skills Work

•Detection: Claude analyzes the request context
•Matching: Compares against skill descriptions
•Loading: Injects skill content into context
•Application: Follows methodology during execution

Progressive Skills Mechanism

mermaid

%%{init: {'theme': 'base', 'themeVariables': {'lineColor': '#64748b'}}}%%
flowchart TB
    classDef main fill:#8b5cf6,stroke:#7c3aed,stroke-width:2px,color:#ffffff
    classDef skill fill:#8b5cf6,stroke:#7c3aed,stroke-width:2px,color:#ffffff
    classDef decision fill:#f59e0b,stroke:#d97706,stroke-width:2px,color:#ffffff

    REQ["🙋‍♀️📥 User Request"] --> MA["🐔 Main Agent"]:::main
    MA --> CHECK{"📚 Match Skills?"}:::decision

    CHECK -->|TDD Task| TDD["📚 test-driven-development"]:::skill
    CHECK -->|Debug Task| DEBUG["📚 systematic-debugging"]:::skill
    CHECK -->|Review Task| REVIEW["📚 code-review"]:::skill
    CHECK -->|None| DIRECT[Direct Execution]

    TDD --> EXEC["✅ Enhanced Execution"]
    DEBUG --> EXEC
    REVIEW --> EXEC
    DIRECT --> EXEC

Example Skill Content

markdown

# .claude/skills/systematic-debugging/SKILL.md

---
description: Use when debugging errors or unexpected behavior - systematic root cause analysis
---

# Systematic Debugging

## Process
1. **Reproduce**: Confirm the issue is reproducible
2. **Isolate**: Narrow down to smallest failing case
3. **Hypothesize**: Form theories about cause
4. **Test**: Verify each hypothesis
5. **Fix**: Apply minimal fix
6. **Verify**: Confirm fix works without regressions

Tips

•Write clear, actionable descriptions
•Include step-by-step methodologies
•Document when to use (and when NOT to use)
•Keep skills focused on single concerns

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