Accurate measurement of tool motion in minimally invasive procedures is an essential component of proficiency assessment. This is particularly important to automate the scoring procedures in, e.g., the Fundamentals of Laparoscopic Surgery (FLS) trainer box. Existing techniques are bulky, require extensive modifications to the surgical tool or trocar mechanism and are expensive. In this work, we propose a new system - the ToolTrack™ consisting of an optical mouse sensor and a MEMS inertial unit that can be easily integrated with any laparoscopic tool, provide accurate and reliable sensing, is light weight and low cost.