14 KiB
Claude Skills Examples
Real-world examples of well-designed skills across different complexity levels and use cases.
Table of Contents
- Simple Skills - Just SKILL.md, no scripts
- Skills with Scripts - Including helper utilities
- Complex Skills - Full-featured with references
- Platform-Specific Skills - Optimized for one platform
- Universal Skills - Work across all platforms
Simple Skills
Example 1: Commit Message Formatter
Use Case: Help developers write conventional commit messages
Structure:
commit-formatter/
└── SKILL.md
SKILL.md:
---
name: commit-formatter
description: Format git commit messages following Conventional Commits. Use when writing commits or reviewing commit history for proper formatting.
---
# Commit Message Formatter
Helps create well-formatted git commit messages following the Conventional Commits specification.
## When to Use
- Writing new commit messages
- Reviewing existing commits for proper format
- Teaching team members commit conventions
- Generating changelogs
## Commit Format
():
```Types
- feat: New feature for users
- fix: Bug fix
- docs: Documentation only changes
- style: Code style changes (formatting, semicolons)
- refactor: Code change that neither fixes a bug nor adds a feature
- perf: Performance improvement
- test: Adding or updating tests
- chore: Maintenance tasks (deps, configs)
- ci: CI/CD changes
Subject Line Rules
- Use imperative mood ("add" not "added")
- No period at the end
- Keep under 50 characters
- Lowercase (except proper nouns)
Body (Optional)
- Wrap at 72 characters
- Explain WHAT and WHY (not HOW)
- Separate from subject with blank line
Footer (Optional)
- Breaking changes:
BREAKING CHANGE: <description> - Issue references:
Closes #123,Fixes #456 - Co-authors:
Co-authored-by: Name <email>
Examples
Simple Feature
feat(auth): add OAuth2 Google login
Bug Fix with Body
fix(api): handle null user service response
The user service occasionally returns null when the user is not
found. This adds proper null checking and returns a 404 status.
Breaking Change
feat(api)!: redesign authentication endpoints
BREAKING CHANGE: The /auth endpoint now requires POST instead of GET.
All clients must be updated to send POST requests with JSON body
containing username and password fields.
Migration guide: https://docs.example.com/v2-migration
Closes #456
Multiple Issues
fix(ui): resolve button alignment in mobile view
Fixes several CSS issues affecting mobile users:
- Button text now wraps properly
- Icons align correctly with text
- Touch targets meet minimum 44px requirement
Fixes #789, #790, #791
Interactive Mode
Just tell me what you changed, and I'll help format it:
Example conversation:
- You: "I added a new login page"
- Me: "Was this a new feature or a fix?"
- You: "New feature"
- Me: "What component/area does this affect?"
- You: "Authentication"
- Me: "Here's your commit message:
feat(auth): add login page"
**Why This Works**:
- Clear, actionable instructions
- Concrete examples for different scenarios
- Covers edge cases (breaking changes, multiple issues)
- Action-oriented description triggers automatic use
- No dependencies or scripts needed
---
### Example 2: JSON Formatter
**Use Case**: Format and validate JSON data
**Structure**:
json-formatter/ └── SKILL.md
**SKILL.md**:
```markdown
---
name: json-formatter
description: Format, validate, and pretty-print JSON data. Use when working with JSON files, API responses, or config files that need formatting or validation.
---
# JSON Formatter
Format and validate JSON data with helpful error messages.
## When to Use
- Format messy JSON
- Validate JSON syntax
- Compare JSON structures
- Convert between compact and pretty formats
- Debug JSON parsing errors
## Features
### 1. Pretty Printing
Transform compact JSON into readable format:
**Input**:
```json
{"name":"John","age":30,"city":"NYC"}
Output:
{
"name": "John",
"age": 30,
"city": "NYC"
}
2. Validation
Check for common JSON errors:
- Missing commas
- Trailing commas
- Unquoted keys
- Single quotes instead of double quotes
- Unescaped characters
3. Minification
Reduce JSON size for transmission:
Input:
{
"users": [
{
"name": "John",
"age": 30
}
]
}
Output:
{"users":[{"name":"John","age":30}]}
4. Structure Analysis
- Count objects, arrays, and primitives
- Find deeply nested paths
- Identify large values
- Detect duplicate keys
Usage
Just paste or upload your JSON and tell me what you need:
- "Format this JSON"
- "Validate this JSON"
- "Minify this JSON"
- "What's wrong with this JSON?"
- "Compare these two JSON files"
Common Fixes
Trailing Comma
❌ {"name": "John", "age": 30,}
✅ {"name": "John", "age": 30}
Single Quotes
❌ {'name': 'John'}
✅ {"name": "John"}
Unquoted Keys
❌ {name: "John"}
✅ {"name": "John"}
Missing Comma
❌ {"name": "John" "age": 30}
✅ {"name": "John", "age": 30}
Tips
- Use JSON for configs (not YAML) when strict validation needed
- Keep nesting under 5 levels for readability
- Consider splitting large JSON files
- Use consistent key naming (camelCase or snake_case)
---
## Skills with Scripts
### Example 3: API Response Validator
**Use Case**: Validate API responses against schemas
**Structure**:
api-validator/ ├── SKILL.md ├── scripts/ │ ├── init.py │ ├── validator.py │ └── schema_builder.py └── README.md
**SKILL.md**:
```markdown
---
name: api-validator
description: Validate API responses against JSON schemas with detailed error reports. Use PROACTIVELY when testing or debugging REST APIs.
tools: Bash, Read, Write
model: sonnet
---
# API Response Validator
Comprehensive validation for API responses.
## Features
- Validate against JSON Schema
- Auto-generate schemas from examples
- Test status codes, headers, body
- Performance metrics
- Security checks
## Usage
### Validate a Response
Validate this API response: { "status": 200, "body": {"user_id": 123, "name": "John"} }
Against schema: { "type": "object", "required": ["user_id", "name"], "properties": { "user_id": {"type": "integer"}, "name": {"type": "string"} } }
### Generate Schema
Generate a schema for this response: {"user_id": 123, "name": "John", "email": "john@example.com"}
### Batch Validation
Validate all responses in ./tests/responses/
## Scripts
This skill includes Python scripts for deterministic validation:
- `validator.py`: Core validation logic
- `schema_builder.py`: Generate schemas from examples
Run manually:
```bash
python scripts/validator.py response.json schema.json
See README.md for detailed script documentation.
**scripts/validator.py**:
```python
#!/usr/bin/env python3
"""Validate JSON against JSON Schema."""
import argparse
import json
import sys
from pathlib import Path
from typing import Any, Dict, List, Tuple
def validate_json(data: Dict[str, Any], schema: Dict[str, Any]) -> Tuple[bool, List[str]]:
"""Validate JSON data against schema.
Returns:
Tuple of (is_valid, error_messages)
"""
errors = []
# Check required fields
if "required" in schema:
for field in schema["required"]:
if field not in data:
errors.append(f"Missing required field: {field}")
# Check field types
if "properties" in schema:
for field, field_schema in schema["properties"].items():
if field in data:
expected_type = field_schema.get("type")
actual_value = data[field]
if not check_type(actual_value, expected_type):
errors.append(
f"Field '{field}' has wrong type. "
f"Expected {expected_type}, got {type(actual_value).__name__}"
)
return len(errors) == 0, errors
def check_type(value: Any, expected_type: str) -> bool:
"""Check if value matches expected JSON type."""
type_map = {
"string": str,
"integer": int,
"number": (int, float),
"boolean": bool,
"array": list,
"object": dict,
"null": type(None),
}
expected_python_type = type_map.get(expected_type)
if expected_python_type is None:
return True # Unknown type, skip check
return isinstance(value, expected_python_type)
def main() -> int:
parser = argparse.ArgumentParser(description="Validate JSON against schema")
parser.add_argument("data_file", type=Path, help="JSON data file")
parser.add_argument("schema_file", type=Path, help="JSON schema file")
args = parser.parse_args()
# Load files
try:
data = json.loads(args.data_file.read_text())
schema = json.loads(args.schema_file.read_text())
except json.JSONDecodeError as e:
print(f"Error: Invalid JSON - {e}", file=sys.stderr)
return 1
except Exception as e:
print(f"Error: {e}", file=sys.stderr)
return 1
# Validate
is_valid, errors = validate_json(data, schema)
if is_valid:
print("✅ Validation passed")
return 0
else:
print("❌ Validation failed:")
for error in errors:
print(f" - {error}")
return 1
if __name__ == "__main__":
sys.exit(main())
Why This Works:
- Combines AI guidance with deterministic validation
- Scripts provide precise, repeatable checks
- Clear examples show usage patterns
- Works across platforms (with network in Code, offline in API)
Complex Skills
Example 4: Database Migration Helper
Use Case: Validate and generate database migrations
Structure:
db-migrator/
├── SKILL.md
├── scripts/
│ ├── __init__.py
│ ├── validate_migration.py
│ ├── generate_rollback.py
│ └── analyze_schema.py
└── references/
├── sql-best-practices.md
├── migration-patterns.md
└── examples.md
SKILL.md:
---
name: db-migrator
description: Create and validate database migrations with automatic rollback generation. Use PROACTIVELY when designing schema changes or creating migration files.
tools: Bash, Read, Write, Edit
model: sonnet
---
# Database Migration Helper
Comprehensive toolkit for database migrations.
## When to Use
- Creating new migrations
- Validating migration safety
- Generating rollback scripts
- Reviewing schema changes
- Planning database refactoring
## Features
### 1. Migration Validation
Checks for:
- Breaking changes (column removal, type changes)
- Performance issues (missing indexes, table locks)
- Data integrity risks (missing constraints)
- Naming conventions
- SQL syntax
### 2. Rollback Generation
Automatically generates rollback scripts for:
- Table creation → DROP TABLE
- Column addition → ALTER TABLE DROP COLUMN
- Index creation → DROP INDEX
- Data migrations → Inverse operations
### 3. Schema Analysis
- Compare schemas across environments
- Identify drift
- Suggest optimizations
- Generate documentation
## Quick Start
### Create a Migration
Create a migration to add an email column to the users table
I'll generate:
- Forward migration (add column)
- Rollback migration (remove column)
- Validation checks
- Index recommendations
### Validate Existing Migration
Validate this migration: [paste your SQL]
I'll check for safety issues and suggest improvements.
### Generate Rollback
Generate rollback for: [paste forward migration]
## Best Practices
For detailed migration patterns and SQL best practices:
Read .claude-plugin/references/sql-best-practices.md
## Scripts
### validate_migration.py
Validates SQL migrations for safety:
```bash
python scripts/validate_migration.py migration.sql
Checks:
- Syntax errors
- Breaking changes
- Performance issues
- Security risks
generate_rollback.py
Creates rollback scripts:
python scripts/generate_rollback.py migration.sql > rollback.sql
analyze_schema.py
Compares schema files:
python scripts/analyze_schema.py schema1.sql schema2.sql
References
- sql-best-practices.md: SQL coding standards and patterns
- migration-patterns.md: Common migration scenarios with examples
- examples.md: Real-world migration examples
Load as needed for detailed guidance.
**Why This Works**:
- Combines AI reasoning with automated checks
- References provide deep expertise without token cost
- Scripts handle deterministic tasks
- Clear separation of concerns
- Works great in Claude Code with full tool access
---
## Summary
### Choosing Skill Complexity
**Simple** (SKILL.md only):
- Documentation formatting
- Writing assistance
- Simple validation
- Template generation
**With Scripts**:
- Data validation
- File processing
- Format conversion
- Code generation
**Complex** (Full featured):
- Multi-step workflows
- Technical domains (databases, APIs)
- Integration with external tools
- Comprehensive validation
### Key Takeaways
1. **Start simple**: Most skills don't need scripts
2. **Add scripts**: When you need deterministic, repeatable operations
3. **Use references**: For detailed specs that don't need to be in context
4. **Test thoroughly**: Ensure skills work as expected
5. **Document well**: Clear examples help users and Claude
### Templates
Use these examples as templates for your own skills:
- Copy the structure
- Adapt the content
- Validate with the validator
- Test thoroughly
- Share with the community!