Pilot: Prompt caching › Ep 7

Ep 7 · Tools, system, messages

1:06

Today's goal: Anthropic builds every request in one order: tools, then system, then messages.

What you'll learn

Change the tools or the model, and everything is rebuilt.
Change the system prompt, and the tools stay cached.
Change a message, and only what comes from there on is redone.
The usage fields show what happened: cache_read_input_tokens, cache_creation_input_tokens and input_tokens.

Sources

Anthropic's prompt-caching reference (as bundled with Claude Code 2.1.299, 21 Oct 2026): render order, what each change invalidates, the usage fields

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