Back to skills
extension
Category: Marketing & GrowthNo API key required

subject-line-optimizer

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.

personAuthor: jakexiaohubgithub

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

| Pattern | Example | Performance | |---------|---------|-------------| | Question | "¿Nos conocemos?" | High | | Contrarian | "A lo mejor esto de la IA sí vale la pena" | 31.84% | | Specific/Technical | "Un minutito: Anatomía de una timestamp" | 31.78% | | Personal | "Lo Que Ando Haciendo" | 31.4% | | Direct benefit | "Busca lo más vital, no más" | 33.52% (best) |

Quick Formulas

Question:     ¿[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

✗ "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

# 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 |