It is still unclear on what and how tool and learner characteristics influence tool use and consequently performance in computer-based learning environments (CBLEs). This study examines the relationships between tool-related characteristics (tool presentation: non-/embedded tool and instructional cues: non-/explained tool functionality) and learner-related characteristics (self-efficacy and goal orientation) as well as their effects on tool use (quantity and quality) and performance in a CBLE. One hundred and forty students, without statically difference in prior knowledge, were randomly assigned to the four conditions (Embedded and non-embedded with explained tool functionality and embedded and non-embedded with non-explained tool functionality) to study a hypertext. Results reveal that embedding tools influenced positively quantity of tool use and negatively quality of tool use. Partial effects of explained tool functionality were found. There were significant interactions of goal orientation (mastery avoidance) and condition on quality of tool use. Performance approach influenced quality of tool positively and self-efficacy influenced negatively quantity of tool use. Only quantity of tool use affected performance. The implications of these results for future research on tool use in CBLE's are discussed. (Contains 3 tables and 8 figures.)