1. A system comprising: one or more processors of a machine; and a machine-readable medium storing instructions that, when executed by the one or more processors, cause the machine to perform operations comprising: receiving a request to generate a message; selecting a generative grammar model from the plurality of generative grammar models in response to receiving the request, the generative grammar model defining a message structure for the requested message, the message structure including a plurality of lexical slots, the generative grammar model specifying: a corpus of source data to populate each lexical slot in the plurality of lexical slots; and a grammatical constraint for each lexical slot in the plurality of lexical slots; generating the message using the generative grammar model; and causing the message to be published on a content publishing platform.