R1 0528 vs Devstral 2 2512

Summary of head-to-head results from our 12-test suite: R1 0528 wins tool_calling (5 vs 4), faithfulness (5 vs 4), classification (4 vs 3), safety_calibration (4 vs 1), persona_consistency (5 vs 4), and agentic_planning (5 vs 4). Devstral 2 2512 wins structured_output (5 vs 4) and constrained_rewriting (5 vs 4). The remaining four tests are ties: strategic_analysis (4/4), creative_problem_solving (4/4), long_context (5/5), and multilingual (5/5). Context from rankings: R1 is tied for 1st in tool_calling, faithfulness, persona_consistency, agentic_planning, and long_context (see displays: tied for 1st with many models), while Devstral is tied for 1st on structured_output and constrained_rewriting. Practical interpretation: R1’s strengths mean fewer incorrect function choices, better adherence to source material, stronger classification/routing, and safer refusals — valuable for assistants, tool orchestration, and customer-facing agents. Devstral’s wins indicate it is more reliable for strict JSON/schema outputs and aggressive compression within hard character limits. Note: in our testing R1 also scored 96.6% on MATH Level 5 and 66.4% on AIME 2025 (Epoch AI) — supplementary external math benchmarks. Operational caveat: R1 has a documented quirk in the payload (may return empty responses on structured_output, constrained_rewriting, and agentic_planning and uses reasoning tokens that consume output budget), so plan for high max_completion_tokens and test structured-output behavior before production use.

Costs are close but meaningful at scale. Per‑million-token prices: R1 0528 input $0.50 / output $2.15; Devstral 2 2512 input $0.40 / output $2.00. Using a 50/50 input/output mix, monthly costs are: 1M tokens — R1 $1.33 vs Devstral $1.20 (difference $0.13); 10M — R1 $13.25 vs Devstral $12.00 (difference $1.25); 100M — R1 $132.50 vs Devstral $120.00 (difference $12.50). High-volume API customers and cost-sensitive production pipelines should prefer Devstral 2 2512 for the small but cumulative savings; teams who need the extra performance on tool calling, safety, and faithfulness may accept R1’s ~7.5% price premium (priceRatio 1.075).

Choose R1 0528 if you need best-in-class tool calling, faithfulness, safety calibration, persona consistency, and agentic planning (it wins 6 of 12 tests and scores 5/5 on tool_calling, faithfulness, persona_consistency, and agentic_planning). Choose Devstral 2 2512 if you need cheaper per-token pricing and top-tier structured-output or constrained-rewriting (Devstral scores 5/5 on structured_output and constrained_rewriting and is $0.10 cheaper input / $0.15 cheaper output per M tokens). If you run millions of tokens per month and strict JSON/schema adherence or length-limited compression is the main requirement, pick Devstral; if your product relies on safe, accurate tool orchestration and faithfulness, accept R1’s modest price premium.