HarnessTax: How Much Does the Harness Matter for Coding Agents?
harnesstax.github.io
September 16, 2026
1 min read
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49/100
Summary
What does a coding-agent harness actually add, and at what cost? It turns out your Claude models may not need Claude Code… We evaluate 21 model–harness pairs spanning seven models and three harnesses—Claude Code, Codex CLI, and Pi—on SWE-bench Lite and Terminal-Bench 2.0.