HarnessTax: How Much Does the Harness Matter for Coding Agents?
HarnessTax is a research project measuring how much the harness, the scaffolding around LLMs, affects coding agent performance.
HarnessTax examines how much the harness — the scaffolding, prompts, and tooling wrapped around a large language model — contributes to coding agent results, as opposed to the underlying model itself. The project was posted on Hacker News on September 16, 2026, where it drew 42 points and 9 comments. Further details are available on the project's GitHub Pages site.