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Learnings from building AI agents

The problem is that, regardless of how you try to use "micro-agents " as a marketing term, LLMs are instructed to return a result.

They will always try to come up with something.

The example provided was a poor one. The comment from LLM was solid. Why would you comment out a step in the pipeline instead of just deleting it? I would comment the same in a PR.

a day agoOras

I've found that giving agents an "opt out" works pretty well.

For structured outputs, making fields optional isn't usually enough. Providing an additional field for it to dump some output, along with a description for how/when it should be used, covers several issues around this problem.

I'm not claiming this would solve the specific issues discussed in the post. Just a potentially helpful tip for others out there.

a day agoSparkyMcUnicorn

Do you have an example of this in practice? I'm having a hard understanding this and have a very similar problem of the agent wanting to give a response on optional fields.

20 hours agobjorgen

Likely because it's temporary?

It takes less effort to re-enable if it's just commented out and its more visible that there is something funky going on that someone should fix.

But yeah, even if it's temporary, it really should have the rationale for commenting it out added... It takes like 5s and provides important context for reviewers and people looking through the file history in the future.

a day agoffsm8

By splitting prompts into smaller chunks you effectively get “bias free” opinions, especially when cross-checked. You can then turn them into local reasoning, which is different from “sending an email to the LLM” which seems to be the case here. Remember, LLM is Rainman.

16 hours agopancsta

Funny thing is the structured output in the last example.

``` { "reasoning": "`cfg` can be nil on line 42; dereferenced without check on line 47", "finding": "Possible nil‑pointer dereference", "confidence": 0.81 } ```

You know the confidence value is completely bogus, don't you?

a day agoelzbardico

Easy fix, just have the LLM generate:

    {
      "reasoning": "`cfg` can be nil on line 42; dereferenced without check on line 47",
      "finding": "Possible nil‑pointer dereference",
      "confidence": 0.81,
      "confidence_in_confidence_rating": 0.54,
      "confidence_in_confidence_rating_in_confidence_rating": 0.12,
      "confidence_in_confidence_rating_in_confidence_rating_in_confidence_rating": 0.98,
      // Etc...
    }
a day agomunificent

confidence all the way down

a day agozengid

Confidence is all you need.

a day agoGardenLetter27

True in many situations in life.

20 hours agolgas

When I was younger and more into music, when I went to a concert I would often judge if a drummer was "good" based on if they were better than me or not. I knew enough about drumming to tell how good someone was at the different parts of having that skill but also knew enough to know that I was not even close to having what it took to be a professional drummer.

This is what I feel like with this blogpost. I've barely scratched the surface of the innards of LLMs but even I know it should be completely obvious to anyone that has a product built around it that these confidence levels are completely made up.

I've never heard or used cubic before today but that part of the blog post, along with the obvious LLM generated quality of it, gives a terrible first impression.

20 hours agoskipants

I too once fell into the trap of having an LLM generate a confidence value in a response. This is a very genuine concern to raise.

a day agoramity

Do you mean that there is no correlation between confidence and false positives or other errors?

a day agosharkjacobs

elzbardico is pointing out how the author is having the confidence value generated in the output of the response rather than it being the confidence of the output.

a day agoramity

Is there research solid knowledge on this?

21 hours agobckr

this trick is being used by many apps (including Github copilot reviews). The way I see it, is that if the agent has an eager-to-please problem, then you give it a way out

19 hours agobaby

Thanks. I was talking about the confidence measure.

14 minutes agobckr

Could you have a higher-order reasoning LLM generate a better confidence rating? That's how eval frameworks generally work today

20 hours agoMattSayar

i immediately noticed the same thing, but to be fair, we don't know if it's enriched by a separate service that checks the response and uses some heuristics to compute that value. If not, yeah, that is an entirely made up and useless value

a day agovolkk

you know everything is made up right? And yet it just works. I too use a confidence score in an bug finder app, Github seems to use them in copilot reviews, people will use them until it is shown not to work anymore.

on the other hand this post https://www.greptile.com/blog/make-llms-shut-up says that it didn't work in their case:

> Sadly, this also failed. The LLMs judgment of its own output was nearly random. This also made the bot extremely slow because there was now a whole new inference call in the workflow.

19 hours agobaby

I think they skipped over a non-obvious motivating example too fast. On first glance, commenting out your CI test suite would be very bad to sneak into a random PR, and that review note might be justified.

I could imagine the situation might actually be more nuanced (e.g. adding new tests and some of them are commented out), but there isn't enough context to really determine that, and even in that case, it can be worth asking about commented out code in case the author left it that way by accident.

Aren't there plenty of more obvious nitpicks to highlight? A great nitpick example would be one where the model will also ask to reverse the resolution. E.g.

    final var items = List.copyOf(...);
    <-- Consider using an explicit type for the variable.

    final List items = List.copyOf(...);
    <-- Consider using var to avoid redundant type name.
This is clearly aggravating since it will always make review comments.
a day agosingron

yep completely agreed, how can that be the best example they chose to use?

If I reviewed that PR, absolutely I'd question why you're commenting that out. There better be a very good reason, or even a link to a ticket with a clear deadline of when it can be cleaned up/reverted

a day agowillsmith72

I agree with the sentiment of this post. I my personal experience the usefulness of a LLM positively correlated with your ability to constrain the problem it should solve.

Prompts like 'Update this regex to match this new pattern' generally give better results than 'Fix this routing error in my server'.

Although this pattern seems true empirically, I've never seen any hard data to confirm this property(?). And this post is interesting but seems like a missed opportunity to back this idea with some numbers.

a day agonzach

This seems like really bad news for the „AI will soon replace all software developers” crowd.

a day agoexitb

what I saw using 5-6 tools like this:

- PR description is never useful they barely summarize the file changes

- 90% of comments are wrong or irrelevant wether it's because it's missing context, missing tribal knowledge, missing code quality rules or wrongly interpret the code change

- 5-10% of the time it actually spots something

Not entirely sure it's worth the noise

a day agoh1fra

code-reviews are not a good use-case for LLMs. here's why: LLMs shine in usecases when their output is not evaluated on accuracy - for example, recommendations, semantic-search, sample snippets, images of people riding horses etc. code-reviews require accuracy.

What is a useful agent in the context of code-reviews in a large codebase is a semantic search agent which adds a comment containing related issues or PRs from the past for more context to human reviewers. This is a recommendation and is not rated on accuracy.

a day agobwfan123

the code reviews can't be effective because the LLM does not have the tribal knowledge and product context of the change. it's just reading the code at face value

a day agoasdev

> 2.3 Specialized Micro-Agents Over Generalized Rules Initially, our instinct was to continuously add more rules into a single large prompt to handle edge cases

This has been my experience as well. However, it seems like the platforms like Cursor/Lovable/v0/et al are doing things differently

For example, this is Lovable’s leaked system prompt, 1550 lines: https://github.com/x1xhlol/system-prompts-and-models-of-ai-t...

Is there a trick to making gigantic system prompts work well?

a day agonico

"51% fewer false positives", how were you measuring? is this an internal or benchmarking dataset?

a day agojangletown

"After extensive trial-and-error..."

IMO, this is the difference between building deterministic software and non-deterministic software (like an AI agent). It often boils down to randomly making tweaks and evaluating the outcome of those tweaks.

a day agomattas

Afaik alchemists had a more reliable method than ... whatever this state of affairs is ^^

a day agos1mplicissimus

You're saying alchemy is better than the scientific method?

a day agosnapcaster

That's because there is no intelligence or understanding involved. They are just trying to brute force a tool for a different purpose into their use case because marketing can't stop overselling AI.

21 hours agoneuronic

Otherwise known as science

1:Observation 2:Hypothesis 3:test 4:GOTO:1

This is every thing ever built ever

What is the problem exactly?

a day agoAndrewKemendo

For one thing, what you learned can stop working when you switch to a new model, or just a newer version of the “same” model.

a day agowrs

The multi agent thing with different roles is so obviously not a great concept, that I am very hesitant to build towards it, even thought it seems to win out right now. We want a AI that internally does what it needs to do to solve a problem, given a good enough problem description, tools and context. I really do not want to have to worry about breaking up tasks into chunks that are smaller than what I could handle myself, and I really hope that that in the near future this will go away.

a day agojstummbillig

People creating products need to do what gives results right now. And I can attest that breaking up jobs into small steps seems to work better for most scenarios. When that becomes unnecessary, creating products that are useful will become much easier for sure, but I wouldn’t hold my breath.

a day agobrabel

I’m not being sarcastic when I say that I think supervisor agents and agent swarms in general are the way forward here

21 hours agobckr

I’ve been testing this for the last few months, and it is now much quieter than before, and even more useful.

a day agovinnymac

When I read "51% fewer false positives" followed immediately by "Median comments per pull request cut by half" it makes me wonder how many true positives they find. That's maybe unfair as my reference is automated tooling in the security world, where the true-positive/false-positive ratio is so bad that a 50% reduction in false positives is a drop in the bucket

a day agoshenberg

I learned from a recent post (https://sean.heelan.io/2025/05/22/how-i-used-o3-to-find-cve-...) that finding security issues can take 100+ calls to an LLM to get good signal. So I wonder about agent implementers who are trying to get good signal out of single calls, even if they are specialized ones.

a day agoiandanforth

I think that article is talking about finding a previously unknown exploit. A known and well documented vulnerability should be much easier to identify

21 hours agobckr

we tried something simple. suprisingly exposed a lot; just ran same input twice through the agent, temp 0. diffed the reasoning trace token by token, didn't expect much honestly. but even small shifts showed up. one run said 'this may introduce risk'. other said 'this could cause issues'.. exact same code. made us realise prompt wasn't grounding the rationale path tight enough. wasn't hallucinating. just the why kept wobbling

a day agob0a04gl

Very vague post light on details, and as usual, feels more like a marketing pitch for the website.

a day agoN_Lens

It's recreating the monolith vs micro-service argument by proxy for a new generation to plan conference talks around.

a day agoweego

I found it useful.

a day agoflippyhead

ah the joy of non-determinism. Have fun tweaking till you die. Also I wish youa lot of fun giving your customers buttons to disable/enable options.

10 hours agohbogert

What's funny about the bullet points in section 3 is that it only compares to the previous noisy agent, rather than having no agent. 51% fewer false positives, median comments per pull request cut by half, spending less time managing irrelevant comments? Turn it off and you could get a 100% reduction in false positives and spend zero time on irrevant AI generated comments.

20 hours agoOnionBlender

What model were they using?

a day agobumbledraven

> Explicit reasoning improves clarity. Require your AI to clearly explain its rationale first—this boosts accuracy and simplifies debugging.

I wonder what models they are using because reasoning models do this by default, even if they don't give you that output.

This post reads more like a marketing blog post than any real world advice.

a day agoEnPissant

> Encouraged structured thinking by forcing the AI to justify its findings first, significantly reducing arbitrary conclusions.

Ah yes, because we know very well that the current generation of AI models reasons and draws conclusions based on logic and understanding... This is the true face palm.

a day agocuriousgal

The "confidence" field in the structured output was what really baffled me.

a day agoelzbardico

Humans work pretty much the same way

Several studies have shown that we first make the decision and then we reason about it to justify it

In that sense, we are not much more rational than an LLM

a day agonico

Humans have a lot more introspection capabilities than any current LLM.

a day agodisgruntledphd2

> Several studies

Please, cite those studies. I want to read them.

a day agoalganet

Lessons.

a day agomosura

https://nolearnings.com/

a day agochanux

I don't like the word learnings either, but you write for your audience and this article was probably written with the hope that it would be shared on LinkedIn.

Learnings might be the right choice here.

I wouldn't complain if the HN headline mutator were to replace "Learnings" with "lessons".

a day agocriddell

This is LITERALLY mind blowing.

a day agoflippyhead
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a day agotempodox

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a day agostavros
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