FGATool is a MATLAB tool for graphical analysis of systems represented with transfer functions having orders of integer and fractional numbers. It offers easy-to-use tools for students and researchers working in the field of system analysis. This paper presents the motivation of its development, an overview of the uncertainty module of the toolbox and the relation with existing tools concerned to system analysis. One of the two main modules of the toolbox is introduced which deals with systems including parametric uncertainties. Analysis tools such as step response, Bode and Nyquist diagrams, interlacing property, root analysis on the first Riemann sheet and value set analysis have been studied overall the toolbox. Main motivation of FGATool lays on its ease of use without much knowledge on mathematical background and its user friendly graphical interface. It also brings more easiness and attraction on fractional order system analysis.