Has Anthropic released anything at all, ever?

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/)

Not voluntarily

It amuses me that that PRs for the claude code source code are still openm

Model Context Protocol

They released it because they knew MCP was slop

safety datasets and a lot of safety related research