Discussion

Simon Willison’s Weblog

CuriouslyC: The halo effect in action.

righthand: How is this different than Prompt Engineering?

deadbabe: I think we all know what Agentic engineering is, the question is when should it not be used instead of classical engineering?

mmastrac: After three months of seeing what agentic engineering produces first-hand, I think there's going to be a pretty big correction.Not saying that AI doesn't have a place, and that models aren't getting better, but there is a seriously delusional state in this industry right now..

giancarlostoro: Prompt engineering was coined before tooling like Claude Code existed, when everyone copied and pasted from chatgpt to their editor and back.Agentic coding highlights letting the model directly code on your codebase. I guess its the next level forward.I keep seeing agentic engineering more even in job postings, so I think this will be the terminology used to describe someone building software whilst letting an AI model output the code. Its not to be confused with vibe coding which is possible with coding agents.

danieltanfh95: Agentic engineering is working from documentation -> code and automating the translation process via agents. This is distinct from the waterfall process which describes the program, but not the code itself, and waterfall documentation cannot be translated directly to code. Agent plans and session have way more context and details that are not captured in waterfall due to differences in scope.

maxbond: I don't think we should be making this distinction. We're still engaged in software engineering. This isn't a new discipline, it's a new technique. We're still using testing, requirements gathering, etc. to ensure we've produced the correct product and that the product is correct. Just with more automation.

ares623: "Prompt" was derogatory /s

pamelafox: I’ve been using the term “agentic coding” more often, because I am always shy to claim that our field rises to the level of the engineers that build bridges and rockets. I’m happy to use “agentic engineering” however, and if Simon coins it, it just might stick. :) Thanks for sharing your best practices, Simon!

neonbrain: The term feels broken when adhering to standard naming conventions, such as Mechanical Engineering or Electrical Engineering, where "Agentic Engineering" would logically refer to the engineering of agents

ares623: Agentic Management doesn't have quite the same ring to it.

ssgodderidge: I agree, partly. I feel the main goal of the term “agentic engineering” is to distinguish the new technique of software engineering from “Vibe Coding.” Many felt vibe coding insinuated you didn’t know what you were doing; that you weren’t _engineering_.In other words, “Agentic engineering” feels like the response of engineers who use AI to write code, but want to maintain the skill distinction to the pure “vibe coders.”

simonw: Prompt engineering didn't imply coding agents. That's the big difference: we are now using tools write and execute the code, which makes for massively more useful results.

iainctduncan: And we haven't even started to see the security ramifications... my money is on the black hats in this race.

simonw: I decided to go with it after z.AI used it in their GLM-5 announcement: https://z.ai/blog/glm-5 - I figured if the Chinese AI labs have picked it up that's a good sign it's broken out.

jdlyga: Sure, you could argue it's like writing code that gets optimized by the compiler for whatever CPU architecture you're using. But the main difference between layers of abstraction and agentic development is the "fuzzyness" of it. It's not deterministic. It's a lot more like managing a person.

simonw: Yeah, Armin Ronacher has been calling it "agentic coding" which does at least make it clear that it's not a general engineering thing, but specifically a code related thing.

skydhash: My preferred definition of software engineering is found in the first chapter of Modern Software Engineering by David Farley Software engineering is the application of an empirical, scientific approach to finding efficient, economic solutions to practical problems in software. As for the practitioner, he said that they: …must become experts at learning and experts at managing complexity For the learning part, that means Iteration Feedback Incrementalism Experimentation Empiricism For the complexity part, that means Modularity Cohesion Separation of Concerns Abstraction Loose Coupling Anyone that advocates for agentic engineering has been very silent about the above points. Even for the very first definition, it seems that we’re no longer seeking to solve practical problems, nor proposing economical solutions for them.

stainlu: The question of when you should not use it is more interesting than the naming debate. Agentic coding works well when the solution space is constrained and verification is cheap: existing tests cover the behavior, the output format is clear, and you can tell whether the result is correct by inspection. CRUD endpoints, data transformations, boilerplate integration code.Where it breaks down is any task where you discover the requirements during implementation. Most hard engineering problems are like this -- you start building, realize the data model is wrong, reshape the abstraction, and iterate. An agent can execute your architecture, but it can't tell you your architecture is the wrong one. That judgment still requires someone who understands the domain deeply enough to notice when the code is solving the wrong problem correctly.The name matters less than recognizing this boundary. Call it agentic engineering or agentic coding, the skill is knowing which tasks to hand to the agent and which to think through yourself first.

simonw: Yeah, I see agentic engineering as a sub-field or a technique within software engineering.I entirely agree that engineering practices still matter. It has been fascinating to watch how so many of the techniques associated with high-quality software engineering - automated tests and linting and clear documentation and CI and CD and cleanly factored code and so on - turn out to help coding agents produce better results as well.

techpression: I mean agents as concept has been around since the 70s, we’ve added LLMs as an interface, but the concept (take input, loop over tools or other instructions, generate output) are very very old.Claude gave a spot on description a few months back,The honest framing would be: “We finally have a reasoning module flexible enough to make the old agent architectures practical for general-purpose tasks.” But that doesn’t generate VC funding or Twitter engagement, so instead we get breathless announcements about “agentic AI” as if the concept just landed from space.

simonw: That definition of software engineering is a great illustration of why I like the term agentic engineering.Using coding agents to responsibly and precisely build good software benefits from all of those characteristics.The challenge I'm interested in is how we professionalize the way we use these new tools. I want to figure out how to use them to write better software than we were writing without them.See my definition of "good code" in a subsequent chapter: https://simonwillison.net/guides/agentic-engineering-pattern...

digdugdirk: Honestly? I've been playing with using LLMs specifically for that reason. I'm far more likely to make prototypes that I specifically intend to throw away during the development process.I try out ideas that are intended to explore some small aspect of a concept, and just ask the LLM to generate the rest of whatever scaffold is needed to verify the part that I'm interested in. Or use an LLM to generate just a roughest MVP prototype you could imagine, and start using it immediately to calibrate my initial intuition about the problem space. Eventually you get to the point where you've tried out your top 3-5 ideas for each different corner of your codebase, and you can really nail down your spec and then its off to the races building your "real" version.I have a mechanical engineering background, so I'm quite used to the concept of destructive validation testing. As soon as I made that connection while exploring a new idea via claude code, it all started feeling much more natural. Now my coding process is far more similar to my old physical product design process than I'd ever imagined it could be.

roncesvalles: I think prompt engineering is obsolete at this point, partly because it's very hard to do better than just directly stating what you want. Asking for too much tone modification, role-playing or output structuring from LLMs very clearly degrades the quality of the output. "Asking the right way" as an art of its own is snake oil-ism.

skydhash: I’ve read the chapter and while the description is good, there’s no actual steps or at least a general direction/philosophy on how to get there. It does not need to be perfect, it just needs to be practical. Then we could contrast the methodology with what we already have to learn the tradeoffs, if they can be combined, etc…Anything that relates to “Agentic Engineering” is still hand-wavey or trying to impose a new lens on existing practices (which is why so many professionals are skeptical)ADDENDUMI like this paragraph of yoursWe need to provide our coding agents with the tools they need to solve our problems, specify those problems in the right level of detail, and verify and iterate on the results until we are confident they address our problems in a robust and credible way.There’s a parallel that can be made with Unix tools (best described in the Unix Power Tools) or with Emacs. Both aim to provide the user a set of small tools that can be composed and do amazing works. One similar observation I made from my experiment with agents was creating small deterministic tools (kinda the same thing I make with my OS and Emacs), and then let it be the driver. Such tools have simple instructions, but their worth is in their combination. I’ve never have to use more than 25 percent of the context and I’m generally done within minutes.

simonw: > there’s no actual steps or at least a general direction/philosophy on how to get thereThat's what the rest of the guide is meant to cover: https://simonwillison.net/guides/agentic-engineering-pattern...

AdieuToLogic: The premise is flawed: Now that we have software that can write working code ... While there are other points made which are worth consideration on their own, it is difficult to take this post seriously given the above.

simonw: If you haven't seen coding agents produce working code you've not been paying attention for the past 3-12 months.

the practice of developing software with the assistance of coding agents.

kevintomlee: the practice of developing software with the assistance of coding agents.Spot on.