Anthropic says in their system card that Claude Sonnet 3.7 showed raw CoTs, and that Claude Opus 4 and Sonnet 4 show raw CoTs unless the CoT is especially long, in which case it is summarized. They also say this summarization happens about 5% of the time. According to the 4.5 system card, Claude Sonnet 4.5 reasoning text works the same way, but instead of giving a number, they say summarization happens in ‘a very small minority of cases’.
I agree that Anthropic and GDM may be reinforcing legibility in some way given how much more structured their CoTs look.
Anthropic says in their system card that Claude Sonnet 3.7 showed raw CoTs, and that Claude Opus 4 and Sonnet 4 show raw CoTs unless the CoT is especially long, in which case it is summarized. They also say this summarization happens about 5% of the time. According to the 4.5 system card, Claude Sonnet 4.5 reasoning text works the same way, but instead of giving a number, they say summarization happens in ‘a very small minority of cases’.
I agree that Anthropic and GDM may be reinforcing legibility in some way given how much more structured their CoTs look.
Claude 4 system card: https://www-cdn.anthropic.com/6d8a8055020700718b0c49369f60816ba2a7c285.pdf#page=8
Claude Sonnet 4.5 system card: https://assets.anthropic.com/m/12f214efcc2f457a/original/Claude-Sonnet-4-5-System-Card.pdf#page=9