Anthropic has a lot of interpretability work, but they are extremely defensive about everything else. Dario doesn't really believe in releasing anything. Despite how he acts in terms of some sort of highly principle driven saviour (machines of loving grace) he clearly is more business minded then anything else.

For example they don't even tell you anything about the tokenization. They even do random chunking and padding to avoid leaking the token strings in the streaming api after it got reverse engineered. (See: https://spylab.ai/blog/claude-tokenizer/)