Back then, LMs were optimized to be great at chatting, but not much else. This meant that agent scaffolds had to get very creative (and complicated) to make LMs perform useful work.
But in 2025, LMs are actively optimized for agentic coding, and we ask:
*What the simplest coding agent that could still score near SotA on the benchmarks?*
*Turns out, it just requires 100 lines of code!*
And this system still *resolves 65% of all GitHub issues in the SWE-bench verified benchmark* with Sonnet 4 (for comparison, when Anthropic launched Sonnet 4, they reported 70% with their own scaffold that was never made public).
Honestly, we're all pretty stunned ourselves—we've now spent more than a year developing SWE-agent, and would not have thought that such a small system could perform nearly as good.
I'll link to the project below (all open-source, of course). The hello world example is incredibly short & simple (and literally what gave us the 65%). But it is also meant as a serious command line tool + research project, so we provide a Claude-code style UI & some utilities on top of that.
We have some team members from Princeton/Stanford here today, let us know if you have any questions/feedback :)
It would be great to have the agent adding a memory (even locally) to avoid mistakes, checking for new versions of libraries, and write a list of tasks first before the execution (similar to Kiro and Trae SOLO).
That's a little bit out of the scope of this project (because we were aiming for the bare minimum of what is needed to get a performative agent — and unfortunately learning from mistake also isn't measured by most benchmarks as they require tasks to be solved independently).
However, you can always add "memory" to agents by asking them to write and read from a file in your repo (Claude.md, cursorrules etc.) You can also try to automate this process and have a mechanism by which the LM decides itself when to put something in them. Similar to how memories work in chatGPT. I think Cursor also recently started doing that.
> checking for new versions of libraries, and write a list of tasks first before the execution
Just add it to the prompt! That's not always desired behavior for a command line helper, but I think it shouldn't be too hard to get it to do that just by prompting alone.
I was just starting to study coding agent implementation, specifically with tool use. Seeing the insight on the README that `bash` is all a modern LLM needs to solve coding tasks was very interesting, since the trend seems to be solidly toward tools.
Being able to read the entire agent code nearly on a single screen is very instructive and inspiring to start hacking.
One thing I'm curious about is API calling efficiency. Did you happen to compare request count or token consumption of the mini agent versus full sized? Is that data available generally for the SWE-bench results?
