---

name: subject-line-optimizer description: | Improve newsletter open rates through better subject lines. Use when: (1) Writing subject lines for tacosdedatos editions, (2) Analyzing why an edition had low open rates, (3) A/B testing subject line variants, (4) Reviewing subject lines before sending. Produces 5-10 variants with recommendations.

Subject Line Optimizer

Improve tacosdedatos open rates (currently 28-33%, target 40%+).

Context: /agents/shared/tacosdedatos-growth-playbook.md for performance data.

Proven Patterns at tacosdedatos

Quick Formulas

CopyQuestion:     ¿[Surprising question about pain point]?
Contrarian:   [Challenge common belief]
Specific:     [Number] [things] para [benefit]
Personal:     [Personal action]: [topic]
Benefit:      [Achieve X] en [time/effort]

Generation Process

1. Identify core value: What's the ONE thing readers get?
2. Generate 5-10 variants across different patterns
3. Check constraints:
   • Under 50 characters (critical info in first 35)
   • Natural Spanish (not Spain-only)
   • Creates curiosity
   • Matches tacosdedatos voice
4. Recommend top 3 with reasoning

What to Avoid

Copy✗ "Newsletter #47"           → No value proposition
✗ "INCREÍBLE TUTORIAL"       → Spammy caps
✗ "¡¡¡No te lo pierdas!!!"   → Desperate punctuation
✗ "¡Mola!"                   → Spain Spanish
✗ Over 60 characters         → Gets cut off

Output Format

Copy# Subject Lines: [Edition Topic]

**Core value**: [One sentence]

## Top Picks

1. **"[Subject]"** (X chars)
   Why: [Reasoning]

2. **"[Subject]"** (X chars)
   Why: [Reasoning]

3. **"[Subject]"** (X chars)
   Why: [Reasoning]

## All Variants

| Pattern | Subject | Chars |
|---------|---------|-------|
| Question | ... | X |
| Contrarian | ... | X |
| etc. | ... | X |