If you have a jury including or composed of frequent submitters of tool ideas, they will often be voting on contestants that include their own submissions. That has the potential to lead to all sorts of problems.

There will be weeks without good contestants and weeks with several, difficult to pick among, contestants. Maybe a longer time period is an answer. Have the moderators, who are currently doing a good job of selecting, pick tools they want included in the monthly "tools of the month" awards. The number picked wouldn't be fixed but would correspond roughly with one tool picked for each week in the month; say somewhere between 2 and 6 tools.