Somebody finally put a logging proxy between the harnesses and the API and measured what actually goes over the wire. Systima did it, and the numbers are not subtle. Claude Code opens a session with roughly 33,000 tokens of system prompt, tool schemas, and injected scaffolding.
Source: [Dev.to](https://dev.to/thegatewayguy/claude-code-burns-5x-more-tokens-before-you-type-a-word-heres-where-they-go-2djb)