Today's Agent Skill: Email Campaign Subject Line Tester
What It Does
Small business email newsletters live or die by their subject lines, yet most owners spend zero time testing them. This skill has your AI agent generate 5 variants of any subject line, predict relative open rates, and flag spam-trigger words — so you can choose the strongest option before you hit send.
How It Works
The agent takes your draft subject line and email goal (promotion, announcement, check-in), then produces five alternatives across different styles: urgency, curiosity, personalization, directness, and benefit-led. It scores each on estimated open-rate potential and identifies any words likely to trigger spam filters.
How to Deploy It
Drop the SKILL.md into your agent's skills folder and trigger it by pasting your draft subject line with a brief note on the email's goal. Compatible with Claude Code, Gemini CLI, Cursor, and Windsurf. Pair with Mailchimp or Klaviyo to A/B test the top two variants before your next send.
SKILL.md — Ready to Deploy
## Description
Generate 5 subject line variants for a small business email campaign, score each for estimated open-rate potential, and flag spam-trigger words.
## Trigger
User provides a draft email subject line and a brief description of the email's goal or content.
## Input
- draft_subject: The user's starting subject line (string)
- email_goal: Short description of what the email is about (e.g., "summer clearance sale", "new service announcement", "re-engage inactive subscribers")
- business_name: Optional — used to personalize subject lines if provided
## Steps
1. Analyze the draft subject line for length (aim for 40–55 characters), sentiment, and any spam-trigger words (e.g., "free", "guaranteed", "act now", "!!").
2. Generate 5 alternative subject lines, one for each style:
- Urgency ("Only 48 hours left...")
- Curiosity ("We've been keeping a secret...")
- Personalization (name or location reference if business_name provided)
- Direct benefit ("Save 30% on X this weekend only")
- Question ("Ready for your best summer yet?")
3. For each variant, note estimated open-rate tier: High / Medium / Low, based on industry benchmarks for small business retail/serviceCopy the full SKILL.md and drop it into your agent's skills directory to activate this skill.