The present invention provides a method and system for dynamically updating descriptions of AV content, such as MPEG-7 content descriptions. One embodiment provides for a method in which first a server issues a command indicating the type of update to make to the description on a client computer. Specifically, the update may be to add, delete, or change a node in a tree or graph structure describing the AV content. For example, the command may specify an update to an instance document or its associated schema. The server also specifies the location in the description to perform the update, which may be at an absolute or relative address. Next, the server sends the data, if any, to be added or used for the change. Embodiments also provide for steps to check that the update is authorized.