This feels like a dumb question, but why doesn't Cursor implement that tool?
I built my own simple coding agent six months ago, and I implemented str_replace_based_edit_tool (https://platform.claude.com/docs/en/agents-and-tools/tool-us...) for Claude to use; it wasn't hard to do.
Maybe this is a flippant response, but I guess they are more of a UI company and want to avoid competing with the frontier model companies?
They also can’t get at the models directly enough, so anything they layer in would seem guaranteed to underperform and/or consume context instead of potentially relieving that pressure.
Any LLM-adjacent infrastructure they invest in risks being obviated before they can get users to notice/use it.