I moved to the US from São Paulo four years ago. My English is good enough that on a call nobody clocks me as a non-native speaker — until they read something I wrote. Then the articles give me away. 'I went to the hospital' versus 'I went to a hospital.' I have been corrected on this, conservatively, two hundred times. Left to my own instincts, I would still flip a coin on it, and the coin would still be wrong about a third of the time.
For two years my crutch was Grammarly. It is a fine tool and I'm not here to dunk on it. It underlines the mistake in red, I click the suggestion, the red goes away, and I feel briefly competent. And then — this is the part that quietly drove me up the wall — I would make the exact same mistake two days later. The correction never became knowledge. It was a vending machine for fixes, not a teacher, and you cannot learn a language one accepted suggestion at a time.
Why being told 'what' never stuck
The reason is obvious in hindsight. A correction without a reason is just a command: click here, trust me, move along. There's nothing to attach the fix to, no rule to generalize from, so it doesn't transfer to the next sentence or the next document. What I actually needed was the thing a good human tutor does — and the thing I could never afford on demand at 11pm before a deadline — which is to explain the rule, every single time, patiently, without sighing or making me feel like a child for not knowing it already.
That's the Proofread Anything and Explain Every Single Correction prompt, and I run it on Claude Opus 4.8. I chose Opus deliberately and I'd defend the choice in a fistfight. Proofreading-with-teaching is genuinely hard: the model needs to know not just that 'discuss about' is wrong but exactly why ('about' is already baked into 'discuss'), and it needs to stay that careful all the way to correction number forty without getting lazy or starting to hand-wave. Opus 4.8 is the model I trust to hold that quality to the bottom of a long document. And for something I'm learning from, accuracy isn't a nice-to-have — a confidently wrong grammar rule would be actively worse than no help, because I'd memorize the wrong thing. It's the one prompt in my whole library I pay for, and the one I'd re-buy without a second of hesitation.
What the output actually looks like
I paste an email, a proposal, sometimes a long Slack message if it's going somewhere that matters. I set the writing level to 'business professional.' Back comes my text with the corrections marked inline, then a table — one row per change, with my original, the fix, and the real rule in plain English. Not 'article error.' Instead: 'Use the for a specific hospital you and the reader both have in mind; use a for any hospital in general.' That sentence did more for me than three years of evening classes where the same rule was a bullet point on a slide I never connected to my own writing.
- Definite vs indefinite articles, explained in context, every time, until it finally became reflex
- Comma splices are fine in a casual blog but not in a report — the level setting catches the difference
- 'Discuss about' is redundant because 'discuss' already contains the 'about'
- My instinct to write one enormous sentence usually reads better as two short, confident ones
- I overuse 'actually' the way some people overuse 'um' — I never noticed until the table kept flagging it
The honest caveat and the result
After about six weeks the article mistake simply stopped happening. Not because I memorized a chart — I'd had charts for years and they did nothing — but because I had seen the same explanation, attached to my own real sentences, twenty-odd times. Repetition with reasons is how anything sticks, and the prompt is patient in a way no human editor has the billable hours to be.
The honest caveat: it's the careful, premium model, so it's slower and pricier than a one-click spell-check, and I don't run it on a throwaway text to my brother. I run it on the things with stakes — the client proposal, the formal email, the message I'd be embarrassed to get wrong in front of people whose opinion I care about. For everyday bloat rather than grammar, I'll reach for my Tighten a Wordy Paragraph to Half Its Length prompt instead, which is faster and free. But when I want to actually get better at the language, this is the one. Grab the Proofread Anything and Explain Every Single Correction prompt on Prompt Dock, run it on the last important thing you wrote, and read the 'why' column instead of just skimming the fixes. That column is the entire point of the thing.