ChatGPT-5.4 is OpenAI’s fastest model yet — 7 prompts that show what it can really do

When OpenAI unveiled GPT-5.4, the company made it clear this wasn’t just another incremental upgrade. The new model combines the coding power of GPT-5.3-Codex with stronger reasoning, improved knowledge work capabilities and the ability to handle much longer, more complex tasks.

In other words, this model is meant to do serious work. Of course, I was skeptical and wondered: How much better is it actually?

To find out, I decided to put GPT-5.4 through a series of prompts designed to test the exact things OpenAI claims it does best. Instead of asking basic questions, I gave the model challenges that required deep reasoning, long-form planning and creative problem solving.

Some of the results were genuinely impressive, others were more surprising. Here are seven prompts I used to see what GPT-5.4 can really do — and how you can try them yourself.

1. The 'long-context' monster prompt

Prompt: I'm going to paste several long documents below. Your job is to synthesize them into one coherent briefing.
Tasks:
1. Identify the 5 most important insights across all documents.
2. Explain how the ideas connect to each other.
3. Highlight any contradictions or disagreements between sources.
4. Write a 300-word executive summary someone could read in under 2 minutes.

With a 1 million token context window, I knew the model could handle a lot. Just how much was something I had to know. After uploading several research documents about the future of work and education in the era of AI, I was immediately impressed by how well the model synthesized the information. This is something older models struggled with – and why I often turned to Claude for this type of prompt.

2. The 'run my project' prompt

Prompt: You are my AI project manager. Goal: Launch a new AI newsletter in 30 days. Create a detailed execution plan including:
- week-by-week milestones
- tools I should use
- content pipeline
- marketing strategy
- launch checklist
Then identify the 3 biggest risks and how to avoid them.

This prompt tests long-term planning and is great for small companies or entrepreneurs on a shoestring budget. I was truly surprised by what ChatGPT-5.4 came up with in just seconds. It was the work of an entire marketing agency without the budget.

3. The 'plan a complex real-life decision' prompt

Prompt: I’m planning a family vacation, but I’m overwhelmed by options. Help me choose between three destinations: Boston, Washington DC, and Montreal.
Consider: travel time from where I live, cost for a family of five
- activities for kids ages 4, 8 and 10
- weather
- overall experience
Create a comparison table and then recommend the best destination with reasoning.
Also provide a 3-day sample itinerary.

Instead of asking GPT-5.4 a simple question, I gave it a real-world decision that requires weighing multiple variables — something AI models have historically struggled with. It's clear this new model has better structured reasoning than previous models. Although not new, the comparison across multiple factors, planning ability and practical usefulness is also evident here.

4. The 'stress-test reasoning' prompt

Prompt: " want you to think like a strategist. Question: Will AI assistants replace smartphones in the next 10 years?
Break your answer into:
1. The strongest argument FOR
2. The strongest argument AGAINST
3. Key technological barriers
4. What would need to happen for it to become likely
5. A probability estimate"

This pushes structured thinking. By asking the model to think like a strategist, it looked at my question from multiple angles then built strong arguments. This prompt could be useful for students looking to understand all sides of their research as well as professionals covering strategies in the boardroom.

5. The “improve my idea” prompt

Prompt: "I have a rough idea for a story: [insert idea]
Your job:
1. Identify what makes the idea interesting.
2. Identify what's weak or unclear.
3. Improve the hook.
4. Suggest 3 stronger titles
5. Turn it into a 3-paragraph agent pitch."

As a writer, my head is always full of ideas for sci-fi books, but are they all good? The problem is, I think so, which is why leaning on AI to bring me back to reality helps. Even though this particular prompt focuses on ideation, it highlights the model’s ability to ideate and get creative, which is another place where AI typically struggles.

6. The 'critic mode' prompt

Prompt: I’m going to give you an argument. Your job is NOT to agree with it.
Instead:
1. Identify logical weaknesses
2. Present the strongest counterargument
3. Suggest what evidence would prove or disprove the claim
4. Rewrite the argument so it becomes much stronger

As a known people pleaser, I thought ChatGPT would surely struggle with this one. However, it looks like this new model is less pleasing and better with reasoning and strategy. I have to say, this update was very necessary for prompts like this one.

7. The 'cross-domain synthesis' prompt

Prompt: "Explain how these three fields intersect:
- artificial intelligence
- economics
- psychology
Then predict one major change that could happen by 2035 because of this intersection."

This prompt tests one of the most advanced capabilities of modern AI models: the ability to synthesize ideas across multiple disciplines. Instead of answering a narrow question, GPT-5.4 has to understand how AI, economics and psychology influence one another, then use that understanding to predict a plausible future outcome. Prompts like this show why cross-domain reasoning is becoming such an important benchmark for AI.

The takeaway

After running GPT-5.4 through these seven prompts, the biggest takeaway is that the model is much better at thinking through problems. Whether it was synthesizing large documents, planning complex projects or evaluating arguments from multiple angles, the model showed stronger structure and reasoning than previous versions. This was obvious right away.

I’m still a little skeptical, but I’m eager to keep testing, reviewing and pushing this model to its limits. Try these prompts yourself by adapting them to your personal or professional needs, then see what kind of results you get. I’d love to hear what you discover in the comments.

Follow Tom's Guide on Google News and add us as a preferred source to get our up-to-date news, analysis, and reviews in your feeds.

More from Tom's Guide

• I asked ChatGPT which streaming services to cancel this month — then used Agent mode to do it
• Your feed is suddenly full of AI cat videos — here’s why they’re going viral right now
• New to Gemini? Here are 7 prompts that instantly show what it can do