Prompt cache reads on Claude Fable 5.1 and Mythos 5.1 drop to $0.25 per MTok
PricingVerifiedAdded Sep 22, 2026
Cache reads on Claude Fable 5.1 and Claude Mythos 5.1 cost 0.025x the base input price instead of the usual 0.1x, which lowers the cost of cache-heavy agent workloads. Cache write pricing is unchanged.
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More Claude Platform releases
Every Claude Platform release| Date | Release | Type |
|---|---|---|
| Sep 1 | Claude Fable 5.1 launches alongside Claude Mythos 5.1 with 1M token context GA | GA |
| Sep 1 | Claude Fable 5.1 and Mythos 5.1 reject tool_choice any and tool Update | Update |
| Sep 1 | Claude Fable 5.1 thinking blocks only replay to the same or newer models Update | Update |
| Sep 1 | Per-message effort changes enter beta on the Claude API Beta | Beta |
| Sep 1 | Claude API adds turn-scoped system messages in beta Beta | Beta |
| Sep 1 | Claude API thinking.display adds an updates mode in beta Beta | Beta |
| Sep 1 | Claude Fable 5.1 output carries text watermarks and C2PA Content Credentials Update | Update |
| Sep 1 | Claude Fable 5.1 and Mythos 5.1 require 30-day data retention Update | Update |
