How do you format skills? Is there a specific format (like YAML)?

Skills are Markdown. Optional YAML-style frontmatter helps Claude parse intent quickly—this pattern works well:

---
name: Generate Tweet
description: Creates an on-brand tweet in Phantom's voice
---

You are writing a tweet for [Brand]. Match the examples below.

INSTRUCTIONS:
- Under 280 characters
- Punchy and direct
- No hashtags unless clearly relevant
- Lead with the product benefit

EXAMPLES:
[paste 3–5 example tweets here]

Keep each skill tight—often roughly 100–300 words. If it balloons, split it. Clear section headers ("INSTRUCTIONS", "OUTPUT FORMAT") beat walls of prose.