Claude Opus 5.5
First of the Claude 5.5 family at $4/$20 per M tokens, now the default Opus in Claude Code.
Why it matters
Near-Fable 5.1 performance at ~40% lower cost and 30%+ faster than Opus 5.
What you could build with it
Trial it as the reviewer agent for a week and measure cost and quality deltas against the current default model.
Does it hold up?
Too early to judge. Launch is roughly two days old and closed-weight, so independent GitHub evidence does not exist yet.
Built with Claude Opus 5.5
- AI Weekly: Opus 5.5, GPT-6 Sol and Luna, and MCPAdev.to · Early testers report real long runs: one agent 18+ hours across six repos; Stripe ran one session directing a dozen more through a multi-day rebase of 40 stacked PRs, all passing CI.
- Claude Opus 5.5: Specs, Benchmarks, Pricing — Kingy AIarticle · Independent benchmark roundup: Opus 5.5 hits 66.4% on Terminal-Bench 4.0 and roughly matches GPT-6 Astra at about 40% of the cost per task.
- Claude Opus 5.5 Is Here: Cheaper and Better — BitsMindsarticle · Review of Anthropic's launch figures: wide coding lead over Fable 5.1 (10.6 points on Terminal-Bench) with narrower gaps outside coding, and 30%+ faster output.
Learn more
First spotted on article: source.
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