Abstract: Disclosed is tool rest for holding tools, materials, and supplies on scaffolding. The tool rest can attach to either the short end or the long side of scaffolding. The tool rest includes a tool tray that is defined by a relatively large, flat horizontal floor surrounded by raised perimeter curb sections. A shelf assembly extends horizontally from one (1) curb section. The shelf assembly includes a flat surface having multiple openings for receiving cup holders or tools. The tool rest clamps to scaffolding posts and includes a mounting assembly having an attachment bracket and at least one (1) angled brace that increases the tool tray loading capacity. The tool rest is detachable and is designed to not interfere with the functionality or safety of the scaffolding.