User finds Opus 5 agents inferior, downgrades to 4.8 for half the cost

papanine · reddit · 2026-08-19

A user compared Anthropic's Opus 5 and Opus 4.8 as subagents within the Fable 5 framework. They observed that Opus 5 frequently missed details and failed instructions, causing excessive loops and token burn. Switching back to Opus 4.8 halved token usage, improved speed, and yielded better output quality. The author concludes Opus 5 has significant issues and plans to avoid it until fixed.

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