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.
But honestly I think sane code organization is the bigger hurdle, which is a lot harder to get right without manual oversight. Which of course leads to the temptation to give up on reviewing the code and just trusting whatever the LLM outputs. But I'm skeptical this is a viable approach. LLMs, like human devs, seem to need reasonably well-organized code to be able to work in a codebase, but I think the code they output often falls short of this standard.
(But yes agree that getting the LLM to iterate until CI passes is table-stakes.)
I think getting good code organization out of an LLM is one of the subtler things - I've learned quite a bit about what sort of things need to be specified, realizing that the LLM isn't actively learning my preferences particularly well, so there are some things about code organization I just have to be explicit about.
Which is more work, but less work than just writing the code myself to begin with.
I don't know anything about DotNet, but I just fired up Claude Code in an empty directory and asked it to create an example dotnet program using the Tomlyn library, it chugged away and ~5 minutes later I did a "grep Deserialize *" in the project and it came up with exactly the line you wanted (in your comment here) it to produce: var model = TomlSerializer.Deserialize<TomlTable>(tomlContent)!;
The full results of what it produced are at https://github.com/linsomniac/tomlynexample
That includes the prompt I used, which is:
Please create a dotnet sample program that uses the library at https://github.com/xoofx/Tomlyn to parse the TOML file given on the command line. Please only use the Tomlyn library for parsing the TOML file. I don't have any dotnet tooling installed on my system, please let me know what is needed to compile this example when we get there. Please use an agent team consisting of a dotnet expert, a qa expert, a TOML expert a devils advocate and a dotnet on Linux expert.
I can't really comment on the code it produced (as I said, I don't use dotnet, I had to install dotnet on my system to try this), so I can't comment on the approach. 346 lines in Program.cs seems like a lot for an example TOML program, but I know Claude Code tends to do full error checking, etc, and it seems to have a lot of "pretty printing" code.
Like when I was trying to find a physical store again with ChatGPT Pro 5.4 and asked it to prepare a list of candidates, but the shop just wasn't in the list, despite GPT claiming it to be exhaustive. When I then found it manually and asked GPT for advice on how I could improve my prompting in the future, it went full "aggressively agreeable" on me with "Excellent question! Now I can see exactly why my searches missed XY - this is a perfect learning opportunity. Here's what went wrong and what was missing: ..." and then 4 sections with 4 subsections each.
It's great to see the AI reflect on how it failed. But it's also kind of painful if you know that it'll forget all of this the moment the text is sent to me and that it will never ever learn from this mistake and do better in the future.
If 80% of the time they 10x my output, and the other 20% I can say "well they failed, I guess this one I have to do manually" - that's still an absolutely massive productivity boost.
I wonder if it was getting blocked on searches or something, and just didn't tell you.
Legit this morning Claude was essentially unusable for me
I could explicitly state things it should adjust and it wouldn't do it.
Not even after specifying again, reverting everything eventually and reprompt from the beginning etc. Even super trivial frontend things like "extract [code] into a separate component"
After 30 minutes of that I relented and went on to read a book. After lunch I tried again and it's intelligence was back to normal
It's so uncanny to experience how much ita performance changes - I strongly suspect anthropic is doing something whenever it's intelligence drops so much, esp. Because it's always temporary - but repeatable across sessions if occuring... Until it's normal again
But ultimately just speculation, I'm just a user after all
And then the next step is to dynamically vary resources based on prediction of user stickiness. User is frustrated and thinking of trying competitor -> allocate full resources. User is profiled as prone to gambling and will tolerate intermittent rewards -> can safely forward requests to gimped models. User is an resolute AI skeptic and unlikely to ever preach the gospels of vibecoding -> no need to waste resources on him.
Honestly, this is my experience. Every now and again it just completely self implodes and gives up, and I’m left to pick up the pieces. Look at the other replies who are making sure I’m using the agrntic loop/correct model/specific enough prompt - I don’t know what they’re doing but I would love to try the tools they’re using.
Maybe Anthropic is trying to cut costs a little and we are all just gaslighting ourselves into thinking its our problem.
I try to give the model as little freedom as possible. That usually means it's not being used for novel work.
But that's the hard part! You can only eke out moderate productivity gains by automating the tedium of actually writing out the code, because it's a small fraction of software engineering.
Then it crawls around for awhile, does some web searches, fetches docs from here and there, whatever. Sometimes it'll ask me some questions. And then it'll finally spit out a plan. I'll read through it and just give it a massive dump of issues, big and small, more questions I have, whatever. (I'll also often be spinning off new planning sessions for pre-work or ancillary tasks that I thought of while reviewing that plan). No structure or anything, just brain dump. Maybe two rounds of that, but usually just one. And then I'll either have it start building, or I'll have it stash in the linear agent so I can kick it off later.
The code it needed to write was:
var model = TomlSerializer.Deserialize<TomlTable>(toml)!;
I remember having to write code on paper for my CS exams, and they expected it to compile! It was hard but I mostly got there. definitely made a few small mistakes though
Friday afternoon I made a new directory and told Claude Code I wanted to make a Go proxy so I could have a request/callback HTTP API for a 3rd party service whose official API is only persistent websocket connections. I had it read the service’s API docs, engage in some back and forth to establish the architecture and library choices, and save out a phased implementation plan in plan mode. It implemented it in four phases with passing tests for each, then did live tests against the service in which it debugged its protocol mistakes using curl. Finally I had it do two rounds of code review with fresh context, and it fixed a race condition and made a few things cleaner. Total time, two hours.
I have noticed some people I work with have more trouble, and my vague intuition is it happens when they give Claude too much autonomy. It works better when you tell it what to do, rather than letting it decide. That can be at a pretty high level, though. Basically reduce the problem to a set of well-established subproblems that it’s familiar with. Same as you’d do with a junior developer, really.
Equating "junior developers" and "coding LLMs" is pretty lame. You handhold a junior developers so, eventually, you don't have to handhold anymore. The junior developer is expected to learn enough, and be trusted enough, to operate more autonomously. "Junior developers" don't exist solely to do your bidding. It may be valuable to recognize similarities between a first junior developer interaction and a first LLM interaction, but when every LLM interaction requires it to be handheld, the value of the iterative nature of having a junior developer work along side you is not at all equivalent.
I simply said the description of the problem should be broken down similar to the way you’d do it for a junior developer. As opposed to the way you’d express the problem to a more senior developer who can be trusted to figure out the right way to do it at a higher level.
What’s giving too much autonomy about
“Please load settings.toml using a library and print out the name key from the application table”? Even if it’s under specified, surely it should at least leave it _compiling_?
I’ve been posting comments like this monthly here, my experience has been consistently this with Claude, opencode, antigravity, cursor, and using gpt/opus/sonnet/gemini models (latest at time of testing). This morning was opus 4.6
Are you using Claude Code? Do yo have it configured so that you are not allowing it to run the build? Because I've observed that Claude Code is extremely good at making sure the code compiles, because it'll run a compile and address any compile errors as part of the work.
I just asked it to build a TOML example program in DotNet using Tomlyn, and when it was done I was able to run "./bin/Debug/net8.0/dotnettoml example.toml", it had already built it for me (I watched it run the build step as part of its work, as I mentioned it would do above).
> I’ve observed Claude code is extremely good at making sure the code compiles
My observation is that it’s fine until it’s absolutely not, and the agentic loop fails.
I don't know that it's useful to assign blame here.
It probably is to your benefit, if you are a coding professional, to understand why your results are so drastically different from what others are seeing. You started this thread saying "I keep getting told I'll be amazed at what it can do, but the tools keep failing at the first hurdle."
I'm telling you that something is wrong, that is why you are getting poor results. I don't know what is wrong, but I've given you an example prompt and an example output showing that Claude Code is able to produce the exact output you were looking for. This is why a lot of people are saying "you'll be amazed at what it can do", and it points to you having some issue.
I don't know if you are running an ancient version of Claude Code, if you are not using Opus 4.6, you are not using "high" effort (those are what I'm using to get the results I posted elsewhere in reply to your comment), but something is definitely wrong. Some of what may be wrong is that you don't have enough experience with the tooling, which I'd understand if you are getting poor results; you have little (immediate) incentive to get more proficient.
As I said, I was able to tell Claude Code to do something like the example you gave, and it did it and it built, without me asking, and produced a working program on the first try.
Oh - I’m blaming Claude not anyone else. I’ve tried again this evening and the same prompt (in the same directory on the same project) worked.
> i don’t know if you’re using an ancient version of Claude code,
I’m on a version from some time last week, and using opus 4.6
> This is why a lot of people are saying "you'll be amazed at what it can do", and it points to you having some issue.
If you look at my comments in these threads, I’ve had these issues and been posting about this for months. I’m still being told “ you’re using the wrong model or the wrong tool or you’re holding it wrong” but yet, here I am.
I’m using plan mode, clearly breaking down tasks and this happens to me basically every time I use the damn tool. Speaking to my team at work and friends in other workplaces, I hear the same thing. But yet we’re just using it wrong or doing something wrong,
Honestly, I genuinely think the people who are not having these experiences just… don’t notice that they are.
We’ve gone from “I’m baffled at your experience” to well yeah it often fails” in two sentences here…
I also clearly said I didn’t allow it one output, I gave it the compile error message, it changed a different line, I told it it was at the affected line and to check the docs. Claude code then tried to query the DLL for the function, abandoned that and then did something else incorrect.
I’m literally asking it to install a package and copy the example from the readme