Generate High-Performing SEM Ad Copy with ChatGPT and Google Best Practices

After 18 years in advertising, I can tell you that writing search ad copy is one of those tasks that sounds simple but eats up a ridiculous amount of time. You need to fit your message into tight character limits, hit the right keywords, follow Google's ever-changing best practices, and produce multiple variations for testing. Multiply that across dozens of campaigns and it becomes a real grind.

So I built something to help: SEM Ad Copy Expert, a custom GPT powered by GPT-4.

I have to admit, this was partly a personal itch-scratching exercise. At work, I'd watch my team spend hours crafting responsive search ads (RSAs) from scratch. I knew there had to be a better way. So I trained a custom GPT on all the publicly available Google best practices for search ads, made sure it understands RSA specifications, and now it does in minutes what used to take hours.

How It Works

It's pretty straightforward:

1. Give it your landing page URL, product information, or answers to a few key questions
2. The tool analyzes the data and generates targeted RSA ad copy
3. The output follows Google RSA specifications automatically

(If the tool can't access your landing page, just copy and paste the content into the chatbox — works fine.)

Why I Think It's Useful

From my experience running SEM campaigns:

• It saves genuine hours of manual copywriting time
• The ad copy is optimized based on analysis of your actual landing page content, not generic templates
• It automatically aligns with Google's latest RSA best practices
• It creates multiple variations, which is exactly what you need for proper A/B testing

A Before/After Example

To make this more concrete, here is what ad copy for a fictional project management tool might look like before and after applying this methodology:

Before (generic, written from scratch):

• Headline 1: "Best Project Management Software"
• Headline 2: "Try Our Tool Today"
• Headline 3: "Manage Projects Easily"
• Description: "Our project management software helps teams work better. Sign up for a free trial today."

After (generated using landing page analysis + Google RSA best practices):

• Headline 1: "Plan, Track & Deliver Projects On Time"
• Headline 2: "Trusted by 10,000+ Teams Worldwide"
• Headline 3: "Free 14-Day Trial — No Credit Card"
• Description: "Reduce project delays by 40% with built-in Gantt charts, real-time dashboards & team collaboration. Start your free trial."

The difference is specificity: real numbers, concrete features pulled from the landing page, a clear call to action with a friction reducer (no credit card), and keyword-rich headlines that align with search intent.

A Prompt Template You Can Use Anywhere

If the custom GPT is unavailable or you prefer using a different LLM, here is a prompt template you can adapt:

You are an expert SEM copywriter. Generate Google Responsive Search Ad (RSA) copy
for the following product/landing page.

LANDING PAGE CONTENT:
[Paste your landing page text or URL summary here]

TARGET KEYWORDS:
[List your primary and secondary keywords]

REQUIREMENTS:
- Generate 15 headlines (max 30 characters each)
- Generate 4 descriptions (max 90 characters each)
- Include at least 3 headlines with target keywords
- Include at least 2 headlines with numbers or statistics from the landing page
- Include at least 1 headline with a clear call to action
- Descriptions should highlight unique selling points and include a CTA
- Follow Google RSA best practices: vary headline themes, avoid redundancy,
  use title case

OUTPUT FORMAT:
List headlines numbered 1-15, then descriptions numbered 1-4.
Flag which headlines contain keywords and which contain CTAs.

"But Why Only Google RSAs?"

Fair question. Three reasons:

• Google has the larger share of paid search advertising, and while Microsoft Ads has its own nuances, the RSA format and best practices overlap significantly
• RSAs are the format for the future — they outperform other formats and work across desktop, mobile, and tablet
• Shopping Ads require product feeds and automation already handles most of the heavy lifting there

A Quick Caveat

This tool is a starting point, not a replacement for human judgment. I'd always recommend reviewing and tweaking the output. AI-generated copy is getting remarkably good, but it still doesn't fully understand your brand voice, your competitive landscape, or the nuances of your specific market. Think of it as a very capable first draft machine :)

Whether you're a search marketing newbie or a PPC veteran, I hope this saves you some time. Let me know if you have any feedback or suggestions — I'm still iterating on it.

Cheers,

Chandler