Methods, computer systems, computer-storage media, and graphical user interfaces are provided for facilitating data transformations, according to embodiments of the present invention. In one embodiment, a set of example values are received. A repository of transformation tools is searched to identify a new transformation tool as relevant to a data transformation associated with the received set of example values. The repository includes annotations associated with the new transformation tool. The new transformation tool is used to generate a transformation program that produces transformed output values. Additional annotations are generated for the new transformation tool based on the transformed output values.