When workers make operational decisions, the firm's global knowledge and the workers’ domain-specific knowledge complement each other. Oftentimes workers have the final decision-making power. Two key decisions a firm makes when designing systems to support these workers are 1) what guidance to deliver and 2) what kind of training (if any) to provide. We examine these choices in the context of mobile money platforms—systems that allow users in developing economies to deposit, transfer, and withdraw money using their mobile phones. Mobile money has grown quickly, but high stockout rates of currency persist due to suboptimal inventory decisions made by contracted employees (called agents). In partnership with a Tanzanian mobile money operator, we perform a randomized controlled trial with 4,771 agents over eight weeks to examine how differing types of guidance and training impact the agents' inventory management. We find agents who are trained in person and receive an explicit, personalized, daily text message recommendation of how much electronic currency to stock are less likely to stock out. These agents are more likely to alter their electronic currency balance on a day (rebalance). In contrast, agents trained in person but who receive summary statistics of transaction volumes or agents who are notified about the program and not offered in-person training do not experience changes in stockouts or rebalances. We observe no evidence of learning or fatigue. Agent-level heterogeneity in the treatment effects shows that the agents who handle substantially more customer deposits than withdrawals benefit most from the intervention.