Field notes
The user interface is the place where every other decision meets reality. A solution can have a well-suited architecture, but if the user cannot get their task done, none of the rest matters.
In the pursuit of shared understanding between all stakeholders, UI sketches are often the single best tool. Everyone understands them, and quickly. Everyone has opinions too. :)
Create one document with sketches for each Bounded Context. Paste in screenshots and describe the screens, the primary user tasks and the states that matter.
The UI-views tab is not a prototyping tool. It is a place to gather existing sketches, screenshots and descriptions, so that all stakeholders see the same thing and can judge whether the rest of the solution proposal actually solves what the user needs.
The actual prototype is better built in HTML or with sketching tools such as Figma. Here we gather the information about the prototype instead, so the various stakeholders can take the proposal in more easily.