The tool(s) shown in the photo are called Snap Ring Pliers.They can be of the internal or external type..most are reversable. The clip on the low level sensor is commonly called a snap ring and with the above shown tool can be easily removed.The tools can be purchased at Auto Zone/Sears and numerous other stores and dont cost much.Good investment in the long term.

Phillip
1992 300CE
1999 C43