o4-mini is cheaper and better across the board; o3 gains 10x compute efficiency on RL, now dominating benchmarks like SEAL and AIME.
June 11, 2026
Summary
o3 and o4-mini introduce end-to-end tool use and multimodal reasoning in chain-of-thought, reducing inference cost per task. Vision and tool capabilities reshape what agents can execute without external orchestration.
Why it matters
o3 and o4-mini introduce end-to-end tool use and multimodal reasoning in chain-of-thought, reducing inference cost per task. Vision and tool capabilities reshape what agents can execute without external orchestration.
Implementation verdict
o4-mini replaces o1-mini for cost-sensitive reasoning tasks. Requires API access (vision/tools not yet available). o3 is 4-5x more expensive than Gemini 2.5 Pro—worth testing for tasks where reasoning ROI justifies cost, but skip for simple completions. Codex CLI (open source) is ready now for code generation workflows.
Sources
Dev Signal
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