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Jev is now available in LangSmith Evals

Blog post from LangChain

Post Details
Company
Date Published
Author
Winston Huynh
Word Count
1,633
Company Posts That Month
21
Language
English
Hacker News Points
-
Post removed?
No
Summary

Jev, a System One model from TypeSafe AI, is now available in LangSmith as a judge for evaluating agent behavior through fast, typed decisions rather than generated text. Unlike deterministic code-based evaluators and slower, less consistent LLM-as-a-judge approaches, Jev assesses states such as agent traces using yes/no probability, multiple-choice, and ordered-score questions, making it suited to high-volume, narrowly defined criteria such as PII leakage, user intent, and frustration. TypeSafe claims Jev is substantially cheaper and faster than comparable LLM classification methods and can evaluate multiple criteria in parallel; a cited test against GPT-5.6 variants and Claude Sonnet 4.6 found that Jev matched human decisions, had much lower variance, averaged 0.44 seconds per call, and cost $0.00035 per call. LangSmith users can configure Jev by adding a TypeSafe API key, selecting the TypeSafe provider and jev-latest model in an evaluator, defining the evaluated state, and adding typed feedback questions, after which results can be filtered, charted, or used to trigger alerts and automations.

Trends Found in this Post
Trend Post Mentions Total Month Mentions Posts Companies MoM
Jev 39 2,144 89 49 -
LLM 23 6,025 1,161 240 +15%
Agent Evaluations 13 210 104 35 +19%
Harness engineering 3 162 112 61 -22%
Observability 3 2,761 730 188 -15%
Secrets Management 1 2,045 503 138 -11%
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