claude-fable-5-1 is live — cache reads fall from $1.00 to $0.25, and APIYI has matched the cut
Anthropic’s new Mythos-class flagship, shipped 1 September, alongside claude-fable-5-1-thinking. The headline change this generation is the cache read price: down from $1.00 to $0.25 / 1M tokens (0.025x base input, versus 0.1x on other Claude models), which lands hardest on long agentic sessions that re-read the same cached prefix. Input at $10 and output at $50 per 1M tokens are unchanged. Our pricing matches the provider line for line — input, output, cache reads and cache writes alike, with cache reads already updated to $0.25. Specs: a 1M token context window, 128k max output, and adaptive thinking always on with depth steered by the effort parameter (default high).
Where it’s available (pick what suits your setup):
default/svipgroups: OpenAI-compatible format,https://api.apiyi.com/v1ClaudeCodegroup: native Anthropic format,https://api.apiyi.com(this group also carries a discount and stacks with recharge bonuses — our own margin given back, separate from the model pricing)
claude-fable-5: forced tool use with tool_choice of any or tool returns 400; thinking blocks are bound to the model that produced them, so switching back to an earlier model mid-conversation loses that turn’s reasoning; and editing earlier turns — rebuilding system or tools, or injecting reminders you later delete — invalidates every later thinking block, which treating the conversation as append-only avoids. On data retention, Fable 5.1 and Mythos 5.1 are Covered Models: inputs and outputs are retained provider-side for 30 days for abuse detection, and APIYI retains no data of its own.
Full specs, benchmark comparisons, and the migration checklist: Claude Fable 5.1 launch deep dive.
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