It’s hard to predict exactly which tools you will need. It depends on the fastener types used in the bread maker construction and the wire connection techniques you use when building the roaster.
The three bread makers I’ve disassembled could all be disassembled with screw drivers with one exception. I had one that used tamper proof fasteners so I had to purchase a set of bits for that model. The bits and screwdriver were somewhere around $10.
The tools you need to connect the wiring depend on the technique you choose to use. At its simplest you could get by with a pair of pliers and a pocket knife to strip wire if you’re just using wire nuts and electricians tape. I don’t recommend using your teeth to strip wires even though I’ve seen my Dad complete wiring projects using his teeth, pliers and electrician’s tape.
If you want a more professional build you will need a wire crimpers and wire strippers. If you choose to use bare crimped connectors with heat shrink you will need a lighter to shrink the wire cover.
In places where I joined two wires to one I soldered the wires on the two wire end of the connection.
When completing the system you will need to cover the portion of the cabinet previously covered by the bread maker controls. Tin snips and a file work fine for rough tin work. A grinder will work for cutting as well. Again, it depends on how you want to accomplish the task.
If you decide to add a switch you will need a drill and drill bit to attach the switch. You can also straight wire the system and have it power up when it’s plugged in if you want to keep the cost of the build down.