nodes array.id and label.type, desc, parent, parents (array), val (size), era, people (array).links array with { source, target } objects, or use parent/parents on nodes (or both).title and description set the viewer header.
{
"title": "My Knowledge Graph",
"description": "connections between ideas",
"nodes": [
{ "id": "root", "label": "Central Idea", "type": "concept" },
{ "id": "a", "label": "Branch A", "type": "tool", "parent": "root" },
{ "id": "b", "label": "Branch B", "type": "person", "desc": "..." }
],
"links": [
{ "source": "root", "target": "b" }
]
}