@shushu this shouldn't be necessary-- i think we want to use metatag module for this.

the metatag module configuration uses the node:summary for all nodes, not just pages. Non-"page" nodes will use the trimmed body value, and "page" nodes already save the meta_description field value as node value. See here: https://github.com/openscholar/openscholar/blob/SCHOLAR-3.x/openscholar/modules/os_features/os_pages/os_pages.field_meta_description.js