Keep it light. mtb wraps existing tools rather than reimplementing them. New features should follow this pattern.
Run mtb on your proposed feature:
mtb consult "your feature idea"
If mtb tells you it already exists, maybe it shouldn't be added.
- Small PRs over large ones
- No new dependencies unless absolutely necessary
- If it can be a separate tool, it probably should be
- Tests should pass
The best contributions add questions that would have prevented real over-engineering you've witnessed. Share the story in your PR.