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A Claude Code user reports Fable sub-agent prompts now auto-append 'reply with ONLY (under 15 lines)' to muzzle Opus 5
An r/ClaudeAI post (169 upvotes, 38 comments) shows Fable, used as an orchestrator over Opus 5 sub-agents, spontaneously adding its own length constraint to every dispatched prompt. The thread's consensus workaround is architectural rather than a prompt tweak: run Fable or Opus 4.6/4.8 as the conversational layer and delegate heavy work to Opus 5 rather than talking to it directly. Anecdotal, but it is a recurring shape in the sub, and it compounds with today's usage-limit story since verbosity is billed.
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