So, I decided to do a little experiment. With Opus 5 just launched, I set it loose on a pretty deep, open-ended task: scan the landscape, dig into niche corners of the web, and find viable, low-competition opportunities to make money online.
Spoiler alert: It completely torched my £20 monthly Cursor credit budget in one sitting, left my workspace looking like a digital bomb site, and handed me virtually zero actionable value.
Here’s what actually happened, why Opus 5 disappointed me, and what you should probably use instead to keep your Cursor credits from evaporating.
The "Analysis": 44 Files of Pure Fluff
When you hand a model a massive, exploratory prompt, you hope for clean, distilled insight. What Opus 5 gave me instead was sheer volume masking as intelligence.
It generated 44 separate analysis files.
Forty-four.
As I clicked through directory after directory, it became clear fast: it was mostly repetitive nonsense, circular logic, and generic market research buzzwords.
And after eating through my entire monthly allowance, do you want to know what its single grand takeaway was?
"You should look into building software to help businesses with their tax management."
Ground-breaking stuff. Truly cutting-edge enterprise strategy. I definitely needed 44 markdown files and a blown credit limit to realize tax software exists.
My Take on Opus 5: Overhyped & Credit-Hungry
From my own experience with this test, Opus 5 is just not that great for deep, multi-step agentic workflows.
It gets bogged down in creating artificial structure, burns through token context at an alarming rate, and ends up giving you high-level common sense wrapped in an impressive-looking file tree. The "context tax" and credit burn rate simply don't match the quality of the actual output.
What You Should Use Instead: Grok 4.5 High Fast
If you’re using Cursor daily for coding, refactoring, or standard project architecture, save your money.
In my experience, sticking with Cursor’s Grok 4.5 High Fast is by far the best use of your monthly credits:
Speed & Efficiency: It doesn't waste time over-generating file bloat.
Cost-Effective: You won't blow through your tier limit on a single run.
Practical Output: It gets straight to the point without hallucinatory rabbit holes.
For almost every real-world task in your IDE, Grok 4.5 High Fast gives you 90% of the reasoning power at a fraction of the cost and time.
The Wildcard: Fable 5?
In hindsight, Fable 5 probably would have been a much better fit for that initial, creative research prompt. Its reasoning style seems better suited for broad-spectrum exploratory tasks without spiraling into a file-creation frenzy.
Unfortunately, I can’t verify that for you right now—because Opus 5 ate my entire credit budget before I could run the comparison!
The Bottom Line
Don't fall into the trap of assuming the most expensive, heavy-weight model will magically solve loose, complex prompts. Keep your Cursor setups clean, save your budget, and stick with Grok 4.5 High Fast for your day-to-day dev workflows. Your wallet (and your file tree) will thank you.
Tell me what your experience of Opus 5 has been....
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