This misses that agentic LLMs are trained via RL to use specific tools. Adding custom tools is subpar to those the model has been trained with. That's why Claude Code has an advantage, over say, Cursor, by being vertically integrated.
Are they really? I've been under impression that agentic LLMs are just instances of the LLMs, no "specialized training" involved
But if one were to write tools that were "abi-compatible" with Claude Code's, could you see similar performance with a custom agent? And if so - is Cursor not doing just that?