What is the recommended way to add image to LLM chat history after calling a tool?

[101scholar]

If a tool calling returns an image instead of texts, how to add it properly to the chat history? My workaround is

def load_screenshot(tool_context: ToolContext):
    """ Load the system screenshot from clipboard.
    """
    if image_bytes := get_clipboard_image():
        tool_context._invocation_context.user_content.parts.append(
            types.Part.from_bytes(
                data=image_bytes,
                mime_type="image/png"
            )
        )
        return "Successfully load screenshot from clipboard."
    else:
        return "Failed to load screenshot from clipboard."

Considering _invocation_context is an internal variable, I guess it is not the traditional way to do this. Then what is the recommended way for this purpose?