In fact, Json as a common language for human in visualization has been around for a while! The benefit of declarative grammar is that users can effective manipulate specs through UI (drag and drop, clicks).
Btw, Flint is intentionally designed to allow agent skip low-level params like scale, axe, zero, step size etc (which are extremely crucial for "GOOD-looking") and they are dynamically optimized by the compiler. So AI agents can have a easier time.
> Json as a common language for human in visualization has been around for a while
Plant, Mermaid, Graphviz are all declarative textual representations designed for human authoring, JSON is made for tools. Its not a criticism just a statement that if interop across agent and human was intended this is not the simplest option.