Opus 5.5 reaches roughly Fable 5.1 performance on most tasks while being faster than Opus 5, and usage limits rise on paid plans, changing which model suits long AI agentAn AI system that doesn't just answer once but works toward a goal in a loop — taking actions, reading the results, and deciding what to do next.Full definition → sessions.
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AI agent — An AI system that doesn't just answer once but works toward a goal in a loop — taking actions, reading the results, and deciding what to do next.
