Claude Models Learn to Manage Memory

Anthropic researchers evaluated how different Claude models manage memory using a learning loop and a Pokémon Red task. Claude Opus 5 was the first model to close the loop, while Sonnet 3.7 wrote 413 memory files. The team found that models like Fable 5 and Opus 5.5 improved by writing fewer, more strategic memory notes to handle long-horizon tasks effectively.