I recently discovered the existence of this fantastic tool, developed by Harvard Graduate School of Education in 2010.
It is specifically aimed at teachers of mathematics and gives a list of aspects of the mathematics classroom that should be in evidence in order to be described as ‘quality instruction’. I can see it being used as the starting point for conversations between teachers for classroom observations. An evaluative tool designed to develop instructional quality, not specifically for teacher evaluation but looking at improving the mathematical learning experienced in classes.
Additionally, Dylan Wiliam recently tweeted about some research that has looked at the link between the use of this tool and student outcomes. That research paper is here.