{
  "context_concept": {
    "id": "ctx_prompt_caching_when_useful",
    "name": "When prompt caching is most useful",
    "category": "prompt_caching",
    "description": "Prompt caching pays off most when the same large prefix (system prompt, tool schema, long reference document, or few-shot examples) is reused across many requests in a short time window, such as a multi-turn agent session or a batch of requests over the same document.",
    "how_it_works": "Each cached prefix has a limited time-to-live; if requests reusing that prefix keep arriving before it expires, subsequent requests keep getting the caching benefit; if too much time passes between requests, the cache entry expires and the next request pays full cost to reprocess and re-cache it.",
    "source_note": "General usage pattern consistent with docs/docs/platform.claude.com/docs/en/build-with-claude/prompt-caching.md.",
    "created_at": "2026-07-02 08:27:03",
    "cite_as": "https://subagentcontext.com/api/context-concepts/ctx_prompt_caching_when_useful"
  }
}