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Tran Tien Van
Tran Tien Van

Posted on Originally published at vandatateam.com

Jev and System One Models: Fast Classifiers for AI Agents

Jev is a System One model that returns typed decisions instead of text. Here's where it fits in an agent loop, what independent tests show, and how to adopt it.

Key takeaways

  • Jev, from TypeSafe AI, is the first System One model: it answers structured questions with probabilities and doesn't generate text.
  • TypeSafe claims 70 to 500 millisecond responses and input pricing of $0.042 per million tokens, with output free.
  • Its headline speed-up figures range from 20x to 193.6x across its own materials. Early independent tests found gains closer to 5x to 10x on real tasks.
  • In 6,003 rubric checks, Jev matched Claude Fable 5.1's verdict 91.5% of the time at roughly 1/200th of the cost.
  • For agent builders, the best fit is fast decisions inside the loop: routing, triage, and guardrails, with an LLM still doing the reasoning.

📖 Read the full guide on Van Data Team → Jev and System One Models: Fast Classifiers for AI Agents

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