I just wrote a complete program in node.js doing it :
var fs = require("fs");
var f = fs.readFileSync('./site.json').toString();
var pages = JSON.parse(f);
for (var key in pages) {
var page = pages[key];
fs.writeFile(
key.replace(/ /g, '_')+'.html',
'<h1>'+page.title+'</h1>'
+ '<p>'+page.description+'</p>'
);
}
If your JSON is in a file named site.json
(note that a comma is missing in your JSON), it writes the two HTML files.