Comment by bluelightning2k

Claude Code and Gemini CLI (and OpenAI Codex) are first party from the respective companies. But also kind of products - in extreme cases people pay $200/month for Claude Code and get $thousands and thousands of usage. There's product bundling there beyond just the interface.

I think Claude Code specifically has a reputation for being a 1st class citizen - as in the model is trained and evalled on that specific toolcall syntax.