Allow %clipboard%, %date%, and {field} variables. Keep it simple where {variables} would trigger popup for user completion; Multiple fields in single prompt would be displayed in simple 2-column table where {Field label:} creates single-line text input field and {{Field Label:}} creates multi-line text input field.

Organize prompts in a flat tree view with drag-and-drop organization (sleeker and more compact, but e.g. https://www.jqueryscript.net/demo/Sortable-Collapsible-Tree-View-Plugin-For-jQuery-Sortable-Lists)

Quick search filter box to instantly find prompts (e.g. "Rephr conc" would match the prompt named "Rephrase title concisely")

Option to resize/maximize/restore/minimize window and remember last used size. Prioritize usability. I want to see the text I am composing.

If user is logged in to logi account w/ confirmed purchase, provide hotkey to call prompt builder when mouse isn't attached.