Unreal Labs open‑sources agent harness, claims 40% saving against Codex
Unreal Agent runs tool calls asynchronously so the model no longer pays tokens to wait, according to the company's benchmark post.
Unreal Labs has released Unreal Agent, an open-source agent harness written in Go, and says it cuts the cost of running coding agents by handling tool calls asynchronously. The company says the design "relieves the underlying model of the need to manage waits, polls, and heartbeats for tools", which lets calls run in parallel without spending tokens on the bookkeeping.
The company reports up to 40% lower cost than Codex on what it describes as production workloads. Its own runs put the harness at 57.9% on Terminal-Bench 4.0 at a total cost of $1,428, 65.8% on SWE-Atlas at $936, and 72.4% on DeepSWE 1.1 at $1,367. On ALE-CLI it reports a 30% full pass rate at $217.
The release on GitHub includes a Go library, a runner executable and the benchmark runner itself, which would let others reproduce the figures. All of the numbers above come from Unreal Labs, and no outside party has checked them.
The post, dated 22 September, reached the Hacker News front page on Tuesday with 217 points and 114 comments. Unreal Labs publishes the code at github.com/unreallabsai/unreal-agent, and says its founders previously worked at CERN and DeepMind.