A document management system utilizes document models for querying, validating, and customizing electronic agreement documents. Document models can be a data structure including document attributes that represent an agreement document. Examples of document attributes include customizable data values, conditions related to the operation of the agreement document and satisfiable by certain values of the customized data values, and rendering parameters for the appearance of the electronic agreement document. The document management system enables a user to create custom document models for generating electronic agreement documents that can be queried, validated, and customized through querying, validating, and customizing the corresponding document models.