News · Claude
Claude announces Opus 5.5 as the first model in its new family
Posted on X by Claude (@claudeai) on 22 September 2026. The headline is our summary; the post itself is quoted below.
Claude@claudeai ·
Introducing Claude Opus 5.5, the first model in our new Claude 5.5 family. It performs at the level of Claude Fable 5.1 for most tasks,…
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Context
- Claude Code 2.1.280Released the same day (UTC). Added Claude Opus 5.5 (claude-opus-5-5), now the default Opus model — 1M context, $4/$20 per Mtok with $0.20/Mtok cache reads · Added mouse support…
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