Unverified50% confidenceFactExact time
Microsoft Azure's configuration page accidentally exposed two unreleased Anthropic models, Fable 5.5 and Mythos 5.5.
1
Sources
50%
Confidence
Short-term (~14 days)
Relevance
11/1/2026
First Seen
Valid until: 11/15/2026
Sources
Related Entities
Related Claims
UnverifiedAnthropic's Opus and Sonnet 5.5 have removed the no-reasoning option, while Haiku 5.5 retains it but performs poorly in that mode.64% similarUnverifiedIn tests with real Agent logs, Haiku 4.5 and Opus 5.5 showed leakage (P=0.050), while Haiku 5.5 and Sonnet 5.5 held.63% similarUnverifiedJudging from the version number, Mythos 5.1 should be an iterative update built on 5.0, which typically implies performance optimization rather than a disruptive architectural change.59% similarUnverifiedAI SDK released version @ai-sdk/perplexity@5.0.0, a major update containing breaking changes.58% similar
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