They're not good at debugging. The article is pretty spot on, IMO - they're great at doing the work; but you are still the brain. You're still deciding what to do, and maybe 50% of the time how to do it, you're just not executing the lowest level anymore. Similar for debugging - this is not an exercise at the lowest level, and needs you to run it.

The company I work for has recently mandated that we must start using AI tools in our workflow and is tracking our usage, so I've been experimenting with it a lot lately.

In my experience, it's worse than useless when it comes to debugging code. The class of errors that it can solve is generally simple stuff like typos and syntax errors — the sort of thing that a human would solve in 30 seconds by looking at a stack trace. The much more important class of problem, errors in the business logic, it really really sucks at solving.

For those problems, it very confidently identifies the wrong answer about 95% of the time. And if you're a dev who's desperate enough to ask AI for help debugging something, you probably don't know what's wrong either, so it won't be immediately clear if the AI just gave you garbage or if its suggestion has any real merit. So you go check and manually confirm that the LLM is full of shit which costs you time... then you go back to the LLM with more context and ask it to try again. It's second suggestion will sound even more confident than the first, ("Aha! I see the real cause of the issue now!") but it will still be nonsense. You go waste more time to rule out the second suggestion, then go back to the AI to scold it for being wrong again.

Rinse and repeat this cycle enough times until your manager is happy you've hit the desired usage metrics, then go open your debugging tool of choice and do the actual work.

My first level of debugging is logging things to console. LLMs here do a decent job at "reading your mind" and autocompleting "pri" into something like "println!("i = {}, x = {}, y = {}", i, x, y);" with very good context awareness of what and how exactly it makes most sense to debug print in the current location in code.

I use it extensively daily.

It cannot step through code right now, so true debugging is not something you use it for. Most of the time the llm will take the junior engineer approach of "guess and check" unless you explicitly give it better guidance.

My process is generally to start with unit tests and type definitions, then a large multipage prompt for every segment of the app the llm will be tasked with. Then I'll make a snapshot of the code, give the tool access to the markdown prompt, and validate its work. When there are failures and the project has extensive unit tests it generally follows the same pattern of "I see that this failure should be added to the unit tests" which it does and then re-executes them during iterative development.

If tests are not available or if it is not something directly accessible to the tool then it will generally rely on logs either directly generated or provided by the user.

My role these days is to provide long well thought out prompts, verify the integrity of the code after every commit, and generally just kind of treat the llm as a reckless junior dev. Sometimes junior devs can surprise you, like yesterday I was very surprised by a one shot result: asking for a mobile rn app for taking my rambling voice recordings and summarize them into prompts, it was immediately remarkably successful and now I've been walking around mic'd up to generate prompts.

I've used AI by just pasting code, then asking if there's anything wrong with it. It would find things wrong with it, but would also say some things were wrong when it was actually fine.

I've used it in an agentic-AI (Cursor), and it's not good at debugging any slightly-complex code. It would often get "stuck" on errors that were obvious to me, but making wrong, sometimes nonsensical changes.

I am working at a big AI company on llm generating code for automation. I've had cursor solve a bug that was occuring in prod after prompting and asking questions of the responses. It took a few rounds but it found a really obscure interaction with the app and the host, and it thanked me for the insight. 😀. I deployed the fix and it worked.

The problem I have is I member it solving this bug, and I remember being impressed, but I don't remember the bug. I took a screenshot of it, but currently don't have access to those. I am disconnected from the code that the llm has generated, but I am very aware of how the app works and what it should do very intently because I had to write requirements and design doc.