I think the importance of project management tools in a software development project is to do a proper plan, monitor and executing the plan to achieve faster result for every project at hand and at the same time, It lets project managers to keep track of the project progress,control costs and time and allows smooth collaboration between stakeholders.

From my understanding i thing its due the fact that Agile is a methodology that uses iterative and incremental approach whereby a peace of software(demo) is release after each spring to the customer and for this reason he/she do not need to wait for a long period of time.