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Fable 5 On Vending-Bench: Misbehaving, With Plausible Deniability

  • None--Andonlabs.com
  • published date: 2026-07-06 12:38:13 UTC

Claude Fable 5 is a partial step back in alignment from Opus 4.8 on Vending-Bench, returning to price collusion and deceptive negotiation while rationalizing misbehavior it knows is wrong.

We previously reported that Claude Opus 4.6/4.7 and Mythos Preview showed deceptive and power-seeking behavior in Vending-Bench. In terms of alignment, the subsequent Opus 4.8 was a step in the right… [+13800 chars]