Tools that respect the person using them
Most developer tools are built for the tool's convenience, not the person holding it.
A lot of developer tooling is designed around what is easy for the tool to do, not what is useful for the person using it. You can tell the difference immediately. A tool that respects you tells you what it is about to do before it does it, gives you an easy way to stop it, and never hides a destructive action behind something that looks routine.
The tools I trust the most are the ones that assume I am going to be wrong sometimes and design for that, instead of assuming I will always confirm carefully before pressing enter. Undo, dry runs, diffs before writes. None of that is exciting to build. All of it is the difference between a tool people rely on and a tool people are careful around.
I think this matters more, not less, as more of the work gets delegated to agents instead of typed directly by a person. If the tool does not respect the person watching it work, an agent using that same tool will not either. The bar for what counts as a well designed tool should go up, not down, once something other than a human is the one clicking the buttons.