The Phillips #00 is what you need to open the mid-2012. The listing doesn't go to 2012 probably because it doesn't work for the late-2012, but it will work for the mid-2012. Make sure you have the right model - the mid-2012 will say Model A1278 on the bottom of the case.
Once the case is open, there may be additional tools needed depending on what you want to do. For RAM, no other tools are necessary but changing the RAM is slightly more difficult than many other computers because the bottom slot is not offset from the top slot. If you're doing a HDD replacement, you need a Torx T6 screwdriver. Changing the battery also requires additional hardware. The iFixit site has a good set of instructions for most of the typical operations. Note: Both the Torx T6 and Phillips #00 screwdrivers can be found at many hardware stores - this is likely not the case with the Pentalobe screwdriver.
https://www.ifixit.com/Device/MacBook_Pro_13"_Unibody_Mid_2012