Providing task-based information

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for providing task-based information are disclosed. In one aspect, a method includes identifying a set of previous interactive sessions for a particular task. For each identified interactive session in the set of previous interactive sessions, a set of implements used during the interactive session are identified based on content of the interactive session. At least one implement in the identified set of implements is classified as a required implement for the particular task. The classification is based, at least in part, on a portion of the previous interactive sessions in which the implement was identified. Classified implements are indexed according to the particular task. Data identifying the indexed implements are provided in response to receipt of a search query referencing the particular task.