kimi-k2-0905-preview vs mistral-medium-3-5

Capability for the money

Not the same tier: mistral-medium-3-5 leads kimi-k2-0905-preview by 27.1 points on following instructions (IFBench), for 2.8× the price. They are level on hard reasoning (GPQA Diamond), so the premium only pays off on following instructions work.

1. Following instructions

   extraction, classification, sticking to a format

   IFBench
   kimi-k2-0905-preview41.7%

   mistral-medium-3-568.8%

   mistral-medium-3-5 +27.1

2. Tool use

   multi-step agent work against real tools

   τ²-bench
   kimi-k2-0905-preview73.4%

   mistral-medium-3-594.2%

   mistral-medium-3-5 +20.8

3. Hard reasoning

   graduate-level science and multi-step analysis

   GPQA Diamond
   kimi-k2-0905-preview76.7%

   mistral-medium-3-574.8%

   kimi-k2-0905-preview +1.9

Averaged over the benchmarks both models sat, kimi-k2-0905-preview returns 59.5 points of pass rate per dollar of blended price against 26.4 — the ratio that decides whether the dearer model earns its rate.

Each figure is a pass rate: the share of that test set the model answered correctly, measured by a third party rather than self-reported by the lab. Rows are different tests of different difficulty, so compare a model against the other model, not one row against the next. No published coding score for one of these models, so that lens is omitted. And a benchmark is not your workload — it narrows the shortlist, it does not pick for you.