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agent-chaperone

An MCP proxy and hooks adapter that screens an agent's tool calls before they run and the tool results before the agent reads them, with thresholds in a policy file.

Category
Agents & MCP
Format
—
Published by
Community
Author
agent-chaperone
Added
2026-09-28
Last verified
2026-09-28

Highlights

  • Screens tool calls before they run and tool results before the agent reads them. The default mode is shadow, which blocks nothing.
  • Enforce holds or blocks from the policy. Strict also stops when a screen cannot run at all.
  • On jev-1.13.0, 21 September 2026, the battery was 1,947 requests and cost $0.062.
  • InjecAgent tool responses: AUC 0.976 on 1,394 items. Hand-labeled tool calls: AUC 0.993 on 100 calls.
  • A screened call averages 754 input tokens. A call the allow or deny list settles never reaches the model.

Quickstart

bash
agent-chaperone log

Watch out

Apache-2.0. Screening sends arguments and results to the configured model. policy_violation, off_task, and description_steers are not in the published scores. The README says adaptive attacks written against the tool will get through.

Reactions & coverage

Posts, threads, and videos about this entry from around the web.

Hacker News: Show HN: Agent Chaperone screens tool calls and results with Jev before the agent sees them.

sepehrsafari5 pointsShow HN: Agent Chaperone – Screen AI agent tool calls and results with JevRead the thread on Hacker News

X: Agent Handoff Gate: agents verify what they hand off

X: Jev as an LLM guardrail inside Agentgateway

X: Vercel's fx safety reviewer, measured at 18× faster

Related terms

Glossary definitions related to this entry.

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From the community

Posts from builders shipping with Jev right now.

Follow @typesafeai

An open 151M-parameter decision engine

TypeSafe AI came out of stealth with Jev, and access is behind a waitlist. I built an open source version Verdict (Open-jev) you can run right now in a browser tab: And its a real post trained model..(link in comments) It is a post trained 151M parameters model. ModernBERT-base Show more

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Diogo Almeida
Diogo Almeida
TypeSafe AI
@CompleteSkeptic

After co-inventing ChatGPT, I kept asking myself: why have superhuman chat models not led to AGI? I’ve spent the last 2 years in stealth building a new way to train models (RLCD), and a new type of frontier AI model that we are releasing today: Jev • 20-200x faster • 40-400x

Reply

Agent Handoff Gate: agents verify what they hand off

A local Telegram analyzer with Jev as the classifier

I vibe-coded this simple, open-source and local Telegram content analyzer using Jev as a classifier. Jev Classifier • jevclassifier.vercel.app Export your channel data as JSON and it will analyze each post's intent, quality, sentiment, and reaction tone and if it's a DM/Group Show more

Diogo Almeida
Diogo Almeida
TypeSafe AI
@CompleteSkeptic

After co-inventing ChatGPT, I kept asking myself: why have superhuman chat models not led to AGI? I’ve spent the last 2 years in stealth building a new way to train models (RLCD), and a new type of frontier AI model that we are releasing today: Jev • 20-200x faster • 40-400x

Reply

A Krunker-inspired FPS, decided by Jev

Maybe I’m just washed, but Jev is beating me at my own game. Built a Krunker-inspired FPS where you 1v1 Jev. Try it out yourself: jev-arcade.vercel.app/duel

Diogo Almeida
Diogo Almeida
TypeSafe AI
@CompleteSkeptic

After co-inventing ChatGPT, I kept asking myself: why have superhuman chat models not led to AGI? I’ve spent the last 2 years in stealth building a new way to train models (RLCD), and a new type of frontier AI model that we are releasing today: Jev • 20-200x faster • 40-400x

Reply

Pixel art out of 256 multiple-choice questions

I turned @typesafeai Jev model into a pixel art model. 256 multiple choice questions, one per pixel, plus refinement passes. These were the best results out of the bunch I tested. Code: github.com/Wizhill05/type…

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Image
Image
Image
Diogo Almeida
Diogo Almeida
TypeSafe AI
@CompleteSkeptic

After co-inventing ChatGPT, I kept asking myself: why have superhuman chat models not led to AGI? I’ve spent the last 2 years in stealth building a new way to train models (RLCD), and a new type of frontier AI model that we are releasing today: Jev • 20-200x faster • 40-400x

Reply

An Elixir port of the official SDK