Dev says Opus 5.5 + Ultracode has the highest ceiling of any model he's tried

curious_vii · x · 2026-09-24

Developer curiousvii reports that Opus 5.5's ceiling with Ultracode is higher than anything he has squeezed from other models, calling it a qualitative improvement akin to 4.5's reliably-strong tool use last November — which is what made JIT context curation via MCP feasible.

Related event: Early testers hail Opus 5.5 as a major leap in capability and autonomy(12 posts)→

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