AI Prompt Caching: 90% Discount on Repeated Context

Anthropic and OpenAI offer prompt caching with up to 90% discounts on cached tokens — huge for chat with long system prompts.

What AI does well here

• Reuse cached system prompts within a 5-minute window.
• Cut latency on subsequent calls with cached prefixes.
• Reduce cost on RAG with stable retrieved chunks.
• Stack with batch APIs for compounding savings.

What AI cannot do

• Cache content that changes per request.
• Persist cache beyond provider-defined TTL (often 5 min).

Practice this safely

Use a small project example from your own work. The useful move is to compare the AI's draft against your goal, sources, and constraints before you trust it.

1. 1Ask AI to explain prompt-cache in plain language, then underline anything that sounds uncertain or too broad.
2. 2Give it one detail from "AI Prompt Caching: 90% Discount on Repeated Context" and ask for two possible next steps plus one reason each step might be wrong.
3. 3Check cost against a trusted source, teacher, adult, expert, or original document before you use it.