Testing multi-tools is mainly using them in every day and task-oriented work. Our test team is selected to include people that work and play with their hands, in remote and simple environments where using a multi-tool enhances their experience instead of becoming a sort of testing burden. In this "real world" environment, we find that we learn the most about a tool's function and quality. However, that environment doesn't teach us all we need to know. We complement the usage testing with a handful of formalized tests that complement, challenge, and add to the findings we gather in the field.
First, we count the functions on the multi-tool. Manufacturers are notoriously generous in their function count. The logical and useful number of functions is often less than what a manufacturer claims. Next, we use each function in its intended application. From this, we deduce actual utility of the function. An included tool shouldn't really "count" if it isn't usable or efficient. Finally, we weight each function. We have long held that the ideal multi-tool includes locking pliers, one-hand deployed blade, scissors, can/bottle opener, file, pocket clip carry (not a function, but something we value highly), and a 1/4" bit driver. When a tool includes one or more of these ideal functions (and none we have found includes all of them), it bumps up the score more than a less-useful function.
Construction Quality is first assessed with a basic, initial impression. Hinge tension, lock action, and rattle-factor in each tool tells a great deal about the overall construction quality of a multi-tool. We have yet to experience a quality issue with a tool that surprised us. Initial impressions are of great value. Further, we perform heavy tasks with the tools intended for heavy use. With every set of pliers, we bend and cut a full-thickness coat hanger. With every blade, we perform at least a few minutes of hardwood whittling. Finally, we use every tool for months, just like you will. If anything, we contrive reasons to use our tested multi-tools so that they will see greater than average "mileage" before we reach any review conclusions.
Use is the only real way to assess ergonomics. We know the attributes that influence ergonomics, but none of it matters until we use the tools in all their intended applications. We look for smooth edges, minimal to no interference between tools, and locks that work smoothly and reliably.
We measure each device for weight, length (closed, pliers, with primary blade, and primary blade effective edge), and thickness (not including any pocket clip). Further, we identify various carry options. An included sheath is nice. Pocket clip carry configuration is very highly regarded. Smaller tools that carry well on a keychain are rewarded for portability.
Our testing process is thorough. We apply years of experience and true professional level perspective and then communicate our findings simply and clearly. There are many, many resources on the web for deeper examinations of multi-tools. None, though, compare products like we do, with the depth of experience we do, and then communicate findings with the casual to the enthusiastic user in mind as we do.