Get Incident:

var gr = new GlideRecord("incident");
    gr.addQuery("number", inputs.number);
    gr.query();
    if (gr.next()) {
        return "Short Description "+gr.getValue('short_description')+" Description "+gr.getValue('description');
    }

Update Incident:

var gr = new GlideRecord("incident");
    gr.addQuery("number", inputs.number);
    gr.query();
    if (gr.next()) {
        gr.category = inputs.category;
        gr.subcategory = inputs.subcategory;
        gr.work_notes = "Category : "+inputs.category +"\n Subcategory : "+inputs.subcategory;
        gr.update();
    }