A retention system is provided for use with a ground engaging tool. The tool retention system may have a generally C-shaped clamp configured to be disposed within an aperture of a work implement and to engage apertures in a tool adapter and a wedge disposed within the apertures of the tool adapter and the work implement and against the generally C-shaped clamp. The retention system may additionally have a generally C-shaped slider disposed within the apertures of the tool adapter to engage the aperture of the work implement and a fastener configured to connect the generally C-shaped slider to the wedge. A retention cap with an expandable retention washer may be secured over a head of the fastener to prevent unwanted rotation.