The AI landscape is evolving faster than ever. Every new breakthrough brings more capability — and often, more complexity.
With each model release, users are confronted with new settings, extra controls, and “advanced options” that can feel less empowering and more overwhelming.
But powerful AI shouldn’t require a steep learning curve. And your workflow shouldn’t have to grow more complicated just because the models do.
What if you could access frontier-level intelligence with zero setup? That’s exactly what the new GPT-5.1 and Claude 4.5 Opus models deliver inside CustomGPT.ai.
When combined with your data, these models don’t just answer questions — they elevate your AI agents into deeper thinkers, sharper analysts, and more capable decision-makers.
And the best part? You can use them immediately on your agents. No manuals. No tuning. No configuration. Just choose a model from the dropdown menu and go.
We’ve pre-optimized everything so you get frontier performance with zero effort.
We did the hard part already
Smarter Models, Zero Added Complexity
The world’s most advanced AI systems shouldn’t require the world’s most advanced setup. Behind the scenes, our engineers spent thousands of hours evaluating model behavior across thousands of real tasks. That includes:
- Testing every configuration
- Benchmarking speed vs. accuracy
- Optimizing system prompts
- Eliminating unnecessary complexity
- Refining reasoning depth
- Validating output stability
- Stress-testing edge cases
The result? All of this engineering ensures that your agents instantly become smarter — without you changing a single setting.
Same interface. Same simplicity. Just dramatically more intelligence.
What’s new
GPT-5.1 for Premium & Enterprise
We’ve introduced two versions of GPT-5.1, each tailored to different styles of work.
GPT-5.1 Optimal
Balanced speed and intelligence. This is now the default for Complex Reasoning agents. It handles 95% of business use cases beautifully.
Ideal for:
- Customer support
- Workflows
- Summaries and synthesis
- Research
- Content transformation
- Operational decisioning
- Cross-department automation
Fast. Capable. Reliable. The version most people should start with — and often stay with.
GPT-5.1 Smart
Designed for deeper thinking and more demanding tasks. Smart prioritizes reasoning quality over response speed.
It excels in:
- Technical or analytical workflows
- Strategic evaluations
- Detailed problem-solving
- Multi-step reasoning tasks
No parameter tuning. No complex setup. Just select from the dropdown and get to work.
Claude 4.5 Opus for Enterprise
Anthropic’s most advanced model, Claude 4.5 Opus, is now available to Enterprise customers.
Opus stands out in areas where ambiguity and nuance matter. While many models excel at structured, well-defined tasks, Opus is built for scenarios where judgment is essential — where the right answer depends on context, subtlety, or trade-offs.
Opus is ideal for:
- Regulatory interpretation
- Strategic decisions with competing trade-offs
- Customer scenarios requiring genuine judgment
- Nuanced reasoning where context changes everything
When you need the equivalent of an expert consultant rather than a fast assistant, Opus is the right choice. When “it depends” is the honest answer, Opus finds the nuance. Enterprise customers can reach out to our sales team for exclusive access.
Which Model Should You Choose?
We keep it simple:
- Start with GPT-5.1 Optimal: It’s our default reasoning model for a reason: fast, accurate, balanced, and powerful.
- Use GPT-5.1 Smart: When you’re handling complex analysis, multi-step reasoning, or detailed technical questions.
- Choose Claude 4.5 Opus: When you need an expert consultant, not just a fast answer. Opus provides deep, nuanced understanding ideal for judgment-heavy tasks.
This structure gives you power without overwhelming you with complexity. Three choices — each optimized for a different style of thinking.
The Best Part? A Seamless Upgrade Experience
One of the challenges with adopting new AI models is the fear of disruption — the idea that upgrading will require reworking workflows, retraining systems, or pausing ongoing projects.
With this update, none of that is necessary. Your existing agents continue operating exactly as they do today, and the transition takes only a moment.
The process is simple:
1. Open Intelligence Settings
2. Select the new model
3. Save your changes
Once you hit save, the upgrade is complete. Your agents don’t need new instructions, and your workflows don’t require any adjustments. Everything stays in place — it just runs better.
In testing, the new model delivered noticeable gains:
These aren’t changes you need to optimize for; they’re improvements that quietly elevate the reliability of your system without adding any operational overhead.
As the underlying technology becomes more capable, your day-to-day experience remains stable — only smoother and more dependable. It’s an upgrade that feels almost invisible, except in the places where it matters most.
Connect With Us
Curious how other teams are using GPT-5.1 and Claude 4.5 Opus in real-world environments? Want to exchange ideas, compare approaches, or explore new workflows?
Join the CustomGPT.ai Slack Community and connect with peers who are building the next generation of AI-powered operations.