What tools does the engineer use to effectively design a project?

Architecture uses all the tools that help in clarifying the idea and the project to the customer, such as 

Freehand drawing 

Drawing on the AutoCAD program and Max 

Figurative work expresses projects 

Tables spaces and other accounts increase the strength of the project

Modeling and simulation, requirements analysis ,Scheduling and mathematical principles

Ms Visio can be use for building proto models.

Every major has its own programs, for example for electrical engineering its a must that you know how to use Ecodial or(etap) for power design and Dialux for lighting design and a tool for drafting AutoCAD is the best choice and recently companies start using Revit instead of AutoCAD

Human Brain in positive way

AutoCad or REVIT can help to attain a perfect design when a perfect mind and hands work on them 

Metrics and scalabilty

knowledge and software ....tools for each  specialist decided engineer .