OptionaltitlePlatform-specific title; maps to each API's title field (e.g. SA fullTitle, YouTube snippet.title).
OptionaldescriptionPlatform-specific description/body text.
OptionaltagsPlatform-specific tags; mapped per API (e.g. YouTube snippet.tags, Vimeo tags).
Optional per-platform overrides for shared draft copy (title, description, tags). When set, distribution uses these values instead of the document-root fields for that platform.