You will naturally and immediately integrate both subjective emotional and logical energy into such a tool, and you probably already have some objective methodologies in mind from past experience. So it's a huge advantage. Just IMO.
Personally I wrote a bunch of my own tools and I found that they taught me a lot about what I really wanted. The tools came and went and new tools were built, but the general lesson-integration flow remains intact and that's the important part.
Prior to that I was too worried about systems maintenance and contingency planning to bother with putting my own tools together, but it turns out that this was easily worked around.
Good luck in achieving your goals.