Just an FYI announcement to Lightroom folks, as of version 20151010.134, my Metadata Wrangler plugin now allows you to add/overwrite certain metadata fields like Title and Caption. Previously, it could merely remove metadata that was already there.

My publish/export plugins generally give a lot of control in how those fields are populated during export, but most other plugins do not, nor do Lightroom's built-in export methods, so those users may appreciate being able to craft their metadata. Through the template tokens that my plugins support, you have access to the breadth of data about the image from your Lightroom catalog, and can use it as you see fit to construct your new metadata fields.

Its length is fairly comical, but here's what the plugin's dialog section now looks like. The new functionality is at the bottom.