When is a coding agent the right tool instead of autocomplete or manual engineering?

Example Answer

The way I'd think about it is this: A coding agent is the right tool when the task requires repo understanding, multi-file reasoning, or an execution loop with search, edits, and verification. For tiny local edits or obvious one-line changes, autocomplete or direct engineering is often faster and easier to trust.

What makes the agent worthwhile is not that it writes code. It is that it can ground itself in the repository, follow a bounded workflow, and do useful work across several steps without losing the thread.

I use agents where the surrounding workflow is expensive for a human to coordinate repeatedly. I avoid them where the task is too open-ended or the blast radius is too high for the current controls.

Common Poor Answer

A weak answer is saying coding agents are for complex coding and autocomplete is for simple coding. The better answer explains repo grounding, execution loop value, and trust boundaries.