OPUS 5 UNDERCUTS FABLE 5: HOW TO PICK YOUR CLAUDE DEFAULT
Anthropic’s Claude Opus 5 is live at about half the price of Fable 5, changing the default model calculus for coding agents. Early coverage pits [Opus 5 vs Fab...
Anthropic’s Claude Opus 5 is live at about half the price of Fable 5, changing the default model calculus for coding agents.
Early coverage pits Opus 5 vs Fable 5, with pricing and capability suggesting Opus 5 gets you close to Fable 5 at a much lower cost. The consolidated Claude model guide lists Opus 5 active at $5/$25 per 1M tokens and Fable 5 at $10/$50, framing a clear cost/perf trade.
For day-to-day engineering, the same guide positions Sonnet 5 as the new default, with a launch price of $2/$10 and a 63.2% SWE-bench Pro score approaching Opus 4.8. That hints most routine tasks land on Sonnet 5, with Opus 5 reserved for harder reasoning.
If you want a quick gut check on real coding economics, this video stacks models in head-to-head tasks: These 4 AI Models Compete. Which Writes Better Code for Less?.
Model choice now has a clear price/performance gradient: Sonnet 5 for routine tasks, Opus 5 for tougher reasoning, Fable 5 when only peak capability matters.
You can likely cut agent costs without losing quality by routing most jobs off premium tiers.
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terminal
Run a week-long A/B on real tickets: Sonnet 5 default with auto-fallback to Opus 5; compare resolution rate, latency, and spend.
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Replay a representative SWE-style task set from your repos and measure defect rate and tool-use success across Sonnet 5 and Opus 5.
Legacy codebase integration strategies...
- 01.
If you’re on Sonnet 4.x or Opus 4.x, pilot Sonnet 5 as default with budget caps and promote to Opus 5 only on failure signals.
- 02.
Track regression risk by diffing PR quality and incident postmortems pre/post switch; keep a rollback flag for critical paths.
Fresh architecture paradigms...
- 01.
Design routing from day one: Sonnet 5 baseline, escalate to Opus 5 on uncertainty, context length, or tool-use retries.
- 02.
Bake cost telemetry into the agent loop so you can tune thresholds without code changes.
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