Don't confuse an ice tool with an ice axe -- they are very different pieces of gear suitable for different environments. An ice axe has a long, straight shaft and curved pick. Ice axes are a mountaineering tool used for ascending snow slopes. An ice tool is shorter, and has a curved shaft and a reverse curved pick. Ice tools are designed specifically for vertical waterfall ice, glacier ice, or mixed rock and ice climbing.
Hybrids between an axe and tool do exist. For instance, a semi-bent shaft with reverse curve pick is suitable for mixed mountaineering. However, they should largely be thought of as different pieces of gear and used according to their intended environment.
Unlike other types of outdoor gear, ice tools have one general design (curved shaft and reverse curve pick) with specific variations. When choosing an ice tool, the most important thing to consider is how the tool feels when you swing it. The best way to measure that is by trying out a wide variety of tools while ice climbing. Another approach is to break each component of the ice tool down and consider how you would use it and what your specific needs are, which is what we will do here.