schema.json

{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "additionalProperties": false,
    "description": "Description of MyObject.",
    "properties": {
        "inner1": {
            "additionalProperties": false,
            "description": "Description of InnerObject.",
            "properties": {
                "foo": {
                    "description": "Description of foo.",
                    "type": "string"
                }
            },
            "required": [
                "foo"
            ],
            "type": "object"
        },
        "inner2": {
            "additionalProperties": false,
            "description": "Override description.",
            "properties": {
                "foo": {
                    "description": "Description of foo.",
                    "type": "string"
                }
            },
            "required": [
                "foo"
            ],
            "type": "object"
        }
    },
    "type": "object"
}