# ClaudeDevs says Opus 5.5 is the first Opus with Fable 5.1-class safeguards

The safeguards cover cyber, bio, and frontier LLM development. Flagged requests fall back to another model, and ClaudeDevs says it is working to reduce incorrect flags.

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Source: ClaudeDevs · Published 9/22/2026, 09:50:21

ClaudeDevs says Opus 5.5 is the first Opus with Fable 5.1-class safeguards on cyber, bio, and frontier LLM development.

Flagged requests fall back to another model. ClaudeDevs says it is working to reduce incorrect flags.

Tags: Opus 5.5, Fable 5.1, Safeguards, ClaudeDevs

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