claude-engineering-plugin/plugins/compounding-engineering/skills/create-agent-skills/references/using-scripts.md

Using Scripts in Skills

Scripts are executable code that Claude runs as-is rather than regenerating each time. They ensure reliable, error-free execution of repeated operations.

<when_to_use> Use scripts when:

• The same code runs across multiple skill invocations
• Operations are error-prone when rewritten from scratch
• Complex shell commands or API interactions are involved
• Consistency matters more than flexibility

Common script types:

• Deployment - Deploy to Vercel, publish packages, push releases
• Setup - Initialize projects, install dependencies, configure environments
• API calls - Authenticated requests, webhook handlers, data fetches
• Data processing - Transform files, batch operations, migrations
• Build processes - Compile, bundle, test runners </when_to_use>

<script_structure> Scripts live in scripts/ within the skill directory:

skill-name/
├── SKILL.md
├── workflows/
├── references/
├── templates/
└── scripts/
    ├── deploy.sh
    ├── setup.py
    └── fetch-data.ts

A well-structured script includes:

1. Clear purpose comment at top
2. Input validation
3. Error handling
4. Idempotent operations where possible
5. Clear output/feedback </script_structure>

<script_example>

#!/bin/bash
# deploy.sh - Deploy project to Vercel
# Usage: ./deploy.sh [environment]
# Environments: preview (default), production

set -euo pipefail

ENVIRONMENT="${1:-preview}"

# Validate environment
if [[ "$ENVIRONMENT" != "preview" && "$ENVIRONMENT" != "production" ]]; then
    echo "Error: Environment must be 'preview' or 'production'"
    exit 1
fi

echo "Deploying to $ENVIRONMENT..."

if [[ "$ENVIRONMENT" == "production" ]]; then
    vercel --prod
else
    vercel
fi

echo "Deployment complete."

</script_example>

<workflow_integration> Workflows reference scripts like this:

<process>
## Step 5: Deploy

1. Ensure all tests pass
2. Run `scripts/deploy.sh production`
3. Verify deployment succeeded
4. Update user with deployment URL
</process>

The workflow tells Claude WHEN to run the script. The script handles HOW the operation executes. </workflow_integration>

<best_practices> Do:

• Make scripts idempotent (safe to run multiple times)
• Include clear usage comments
• Validate inputs before executing
• Provide meaningful error messages
• Use set -euo pipefail in bash scripts

Don't:

• Hardcode secrets or credentials (use environment variables)
• Create scripts for one-off operations
• Skip error handling
• Make scripts do too many unrelated things
• Forget to make scripts executable (chmod +x) </best_practices>

<security_considerations>

• Never embed API keys, tokens, or secrets in scripts
• Use environment variables for sensitive configuration
• Validate and sanitize any user-provided inputs
• Be cautious with scripts that delete or modify data
• Consider adding --dry-run options for destructive operations </security_considerations>