prompt-caching-ttl
Installation
SKILL.md
Prompt Caching — 5min & 1h TTL
Prompt caching reuses already-processed prefixes. Cache reads cost ~10% of fresh input. For apps with large repeated context, this is the single biggest lever on your bill.
When to Use
- Large system prompts reused across many requests
- Long documents/codebases with many follow-up questions
- Multi-turn conversations with growing history
- Tool/function definitions shared across sessions
- Any call where > 1024 tokens would be repeated (2048 for Haiku)
Two TTLs
| TTL | Use case | Cost of cache write |
|---|---|---|
| 5 min (ephemeral) | Conversation, active session, interactive tools | ~1.25× input |
| 1 hour | System prompts, knowledge bases, codebases | ~2× input |