kapynResearch

Fancy harnesses make coding agents more expensive but not better, study finds

A study finds that switching between coding‑agent harnesses such as Claude Code, OpenCode, or mini‑SWE‑agent barely improves pass rates but can triple cost per task, mainly due to the system prompt being resent each step. The findings suggest that harness choice adds expense without performance gains for developers.

The Decoder·Oct 24, 2026

Opening Kapyn…