Minecraft wiki entry for Raw_JSON_text_format, associated text: Certain text content types ( score,  selector, and  nbt) do not work in all contexts. These content types need to be resolved, which involves retrieving the appropriate data from the world, rendering it into "simple" text components, and replacing the "advanced" text component with that. This resolution can be done by signs, by written books when they are first opened, and by commands such as /tellraw and /title. It can also be done by the item modifers set_name and set_lore, but only if their  entity tag is set. Custom item names and custom entity names cannot by themselves resolve these components.