The real magic of LLMs comes when they iterate until completion until the code compiles and the test passes, and you don't even bother looking at it until then.
Each step is pretty stupid, but the ability to very quickly doggedly keep at it until success quite often produces great work.
If you don't have linters that are checking for valid syntax and approved coding style, if you don't have tests to ensure the LLM doesn't screw up the code, you don't have good CI, you're going to have a bad time.
LLMs are just like extremely bright but sloppy junior devs - if you think about putting the same guardrails in place for your project you would for that case, things tend to work very well - you're giving the LLM a chance to check its work and self correct.
It's the agentic loop that makes it work, not the single-shot output of an LLM.
There are techniques that can help deal with this but none of them work perfectly, and most of the time some direct oversight from me is required. And this really clips the potential productivity gains, because in order to effectively provide oversight you need to page in all the context of what's going on and how it ought to work, which is most of what the LLMs are in-theory helping you with.
LLMs are still very useful for certain tasks (bootstrapping in new unfamiliar domains, tedious plumbing or test fixture code), but the massive productivity gains people are claiming or alluding to still feel out of reach.
For instance, if you are working on a compiler and have a huge test database of code to compile that all has tests itself, "all sample code must compile and pass tests, ensuring your new optimizer code gets adequate branch coverage in the process" - the underlying task can be very difficult, but you have large amounts of test coverage that have a very good chance at catching errors there.
At the very least "LLM code compiles, and is formatted and documented according to lint rules" is pretty basic. If people are saying LLM code doesn't compile, then yes, you are using it very incorrectly, as you're not even beginning to engage the agentic loop at all, as compiling is the simplest step.
Sure, a lot of more complex cases require oversight or don't work.
But "the code didn't compile" is definitely in "you're holding it wrong" territority, and it's not even subtle.
If you read my post, you’d see that Claude code didn’t do that, I had to intervene in the agent loop and when I did it undid my fixes.
In fact, I find that with a strict feedback loop set up (i.e. a lot of lint rules, a strict type checker and fast unit tests), it will almost always generate what I want.
As someone else said, each step might be pretty stupid, but if you have a fast iteration loop, it can run until everything passes cleanly. My recommendation is to specify what really counts as "done" in your AGENTS.md/CLAUDE.md.
I didn't give my Agent any tools, it hallucinated code.
...well, yes. It's like evaluating a programmer's skill by having one-shot a program on paper with zero syntax errors.
