Claude Code reportedly dropped more than 80% of its system prompt for Opus 5
nreece · hn · 2026-07-25
Claim in the post
A tweet says more than 80% of Claude Code’s system prompt was removed for Opus 5 and Fable 5.
If accurate, that would suggest a major simplification of the agent’s instruction layer and a notable change in how Claude Code is steered internally.
The post itself is a pointer to the original tweet, so the key takeaway is the alleged prompt reduction, not any additional implementation detail.
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