That’s why it’s just easier to work in the original units of the recipe instead of needlessly converting it for nor real benefit. We’re making a single batch of cookies, not bread for an army or drugs; SI units and excessive precision just don’t matter that much. The recipe isn’t vague, just your understanding. A tablespoon isn’t a vague measurement, you’re just trying to adapt it to a needlessly precise unit of measure and forgetting everything your maths and sciense teachers should have taught you about significant digits.