Opus 4.8 Reported to Have Regressed in Tool Calling
mitsuhiko · x · 2026-07-05
Prominent developer Armin Ronacher (mitsuhiko) found that the latest Opus 4.8 and Sonnet fail when calling Pi's edit tool, an issue absent in older versions. He had previously suspected that the new Opus was degrading on tasks outside its training distribution; he has now gathered evidence and written an analysis on this capability regression.
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