Claude Fable 5 Isn't Nerfed. The Router Is Just Paranoid

An important story is making waves across the blockchain ecosystem. In brief BridgeBench's debugging score for Claude Fable 5 dropped from 86. 9 after its July 1 reinstatement—but the collapse came from the safety classifier routing most tasks to Opus 4.

8, not from the model getting dumber. AI ran thousands of blind human-preference votes and found Fable 5's performance mostly flat versus the June version, with some categories—document and expert text—actually improving after reinstatement.

Anthropic has acknowledged its new classifiers will produce false positives on routine coding and debugging, and says the system will be refined over time—but has given no timeline.

This shift continues to shape the digital-asset landscape, with analysts examining its near-term effects.