Agent skill

Use Jev

Use Jev, a general classifier, for typed choices, scores, and yes/no probabilities in software.

MITAuto-check passed

Install Use Jev

skills CLI

$ npx skills add OpenHands/extensions --skill use-jev -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install OpenHands/extensions use-jev --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/OpenHands/extensions.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/use-jev .claude/skills/use-jev && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "use-jev" agent skill from https://github.com/OpenHands/extensions/tree/main/skills/use-jev into .claude/skills/use-jev/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "use-jev", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/OpenHands/extensions/tree/main/skills/use-jev

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add OpenHands/extensions --skill use-jev -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install OpenHands/extensions use-jev --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/OpenHands/extensions.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/use-jev .agents/skills/use-jev && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "use-jev" agent skill from https://github.com/OpenHands/extensions/tree/main/skills/use-jev into .agents/skills/use-jev/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "use-jev", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add OpenHands/extensions --skill use-jev -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install OpenHands/extensions use-jev --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/OpenHands/extensions.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/use-jev .cursor/skills/use-jev && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "use-jev" agent skill from https://github.com/OpenHands/extensions/tree/main/skills/use-jev into .cursor/skills/use-jev/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "use-jev", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/OpenHands/extensions.git --path skills/use-jev

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add OpenHands/extensions --skill use-jev -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install OpenHands/extensions use-jev --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/OpenHands/extensions.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/use-jev .gemini/skills/use-jev && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "use-jev" agent skill from https://github.com/OpenHands/extensions/tree/main/skills/use-jev into .gemini/skills/use-jev/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "use-jev", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install OpenHands/extensions use-jev

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add OpenHands/extensions --skill use-jev -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/OpenHands/extensions.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/use-jev .github/skills/use-jev && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "use-jev" agent skill from https://github.com/OpenHands/extensions/tree/main/skills/use-jev into .github/skills/use-jev/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "use-jev", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add OpenHands/extensions --skill use-jev -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install OpenHands/extensions use-jev --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/OpenHands/extensions.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/use-jev .opencode/skills/use-jev && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "use-jev" agent skill from https://github.com/OpenHands/extensions/tree/main/skills/use-jev into .opencode/skills/use-jev/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "use-jev", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: use-jev
GitHub stars: 157
Token cost: ~806 tokens
SKILL.md length: 186 words
Files: 5
Skills in repo: 78
Repo updated: Oct 6, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Use Jev, a general classifier, for typed choices, scores, and yes/no probabilities in software.

Needs JEV_API_KEY

What it does

Use Jev is an agent skill from OpenHands/extensions. Use Jev, a general classifier, for typed choices, scores, and yes/no probabilities in software.

Its SKILL.md is about 810 tokens, which your agent loads only when the skill is triggered. The skill folder holds 5 other files (for example `.plugin/plugin.json` and `README.md`).

The repository describes itself as: Public registry for OpenHands extensions. The licence is MIT.

Example prompts

“/use-jev”

Requirements

Python 3
A credential in JEV_API_KEY

What it can do on your machine

Read from SKILL.md and the folder at commit d008b81. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are python).
From the folder's file list and the shell code blocks in SKILL.md.
Network
Links to these hosts (documentation or services it may open):
- docs.typesafe.ai
- typesafe.ai
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names these keys or tokens, usually read from environment variables:
- JEV_API_KEY
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Use Jev loads about 806 tokens when it runs. Until then it costs about 26 tokens; SKILL.md has 186 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~26
When it runs · the whole SKILL.md, loaded when a task matches: ~806

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from OpenHands/extensions at commit d008b81, republished under its MIT licence (© OpenHands). 186 words, ~806 tokens.

Download SKILL.mdSave it as .claude/skills/use-jev/SKILL.md (or your agent's skills folder). This skill also uses 4 other files; get the full folder from GitHub.

name: use-jev
description: Use Jev, a general classifier, for typed choices, scores, and yes/no probabilities in software.
triggers: jev

Jev is a newly released general classifier. Give it text or application state and typed questions; it returns decisions and probabilities your code can use for routing, ranking, extraction, or verification.

Read the upstream llms.txt to find current documentation, then follow the pages relevant to the task:

Use cases: explore applications; see worked examples for function calling, reranking, and citation checks.
Best practices: provide relevant state, ask focused questions, define clear criteria, and batch independent questions. Keep workflow logic in code.
Confidence: use uncertainty to decide when to escalate, and validate thresholds on representative data.
Python SDK, JavaScript SDK, or HTTP API: read before integrating.

Choice, Score, and Noul

Primitive	Example use	Result
Choice	Route a support request to a team	One option, option probabilities, and confidence
Score	Rate a bug's impact	Probability-weighted position on ordered levels, plus confidence
Noul	Check whether a refund is requested	Probability of yes; 0.5 means uncertainty, not medium intensity

Install typesafe-sdk and check that JEV_API_KEY is set in the environment, otherwise ask the user to provide it. This Python example asks one question of each type in a single call:

python

import os

from typesafe_sdk import Choice, Noul, Score, TypeSafeClient

with TypeSafeClient(api_key=os.environ["JEV_API_KEY"]) as client:
    result = client.system_one(
        state={"ticket": "PDF export fails, but CSV works. Please refund this month."},
        questions={
            "team": Choice(
                instructions="Which team should handle the main issue in the ticket?",
                criteria={"billing": "Charges and payments",
                          "technical": "Broken product features", "other": "Neither"},
            ),
            "impact": Score(
                instructions="How much does the reported bug affect functionality?",
                criteria=["Cosmetic only", "Feature broken; workaround available",
                          "Work blocked; no workaround available"],
            ),
            "refund": Noul(instructions="Does the ticket explicitly request a refund?"),
        },
    )

print(result.choices["team"].choice)
print(result.scores["impact"].score)
print(result.nouls["refund"].noul)

Files

SKILL.md and 4 other files in skills/use-jev of OpenHands/extensions.

SKILL.md
.claude-plugin
.codex-plugin
.plugin/plugin.json
README.md

Open the folder on GitHubat commit d008b81

Compare with similar skills

Use Jev next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Use Jev compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Use Jev this skillOpenHands/extensions	157	—	~806	Automated safety check: Pass	MIT	yesterday
Rust Path Typesopeninterpreter/openinterpreter	69k	2 repos	~605	Automated safety check: Pass	Apache-2.0	today
Python Type Safetywshobson/agents	40k	—	~1.4k	Automated safety check: Pass	MIT	3 days ago
Pyrefly Type Coveragepytorch/pytorch	104k	—	~3k	Automated safety check: Pass	Custom licence	today
Omh Jev Askrlaope/oh-my-hermes	3.2k	—	~673	Automated safety check: Pass	MIT	today
Typescript Advanced Typesrolling-scopes/rsschool-app	10k	24 repos	~4.2k	Automated safety check: Pass	MPL-2.0	3 days ago

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Questions about Use Jev

What does Use Jev do?

Use Jev, a general classifier, for typed choices, scores, and yes/no probabilities in software. Use Jev is an agent skill from OpenHands/extensions. Use Jev, a general classifier, for typed choices, scores, and yes/no probabilities in software.

How do I install Use Jev in Claude Code?

Run `npx skills add OpenHands/extensions --skill use-jev -a claude-code`. Or copy the skill folder (skills/use-jev in OpenHands/extensions) into .claude/skills/use-jev in your project. Claude Code loads it when a task matches its description.

How do I install Use Jev in Codex?

Run `npx skills add OpenHands/extensions --skill use-jev -a codex`. Or copy the skill folder (skills/use-jev in OpenHands/extensions) into .agents/skills/use-jev in your project. Codex loads it when a task matches its description.

Can I use Use Jev in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add OpenHands/extensions --skill use-jev -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/use-jev, .gemini/skills/use-jev, .github/skills/use-jev and .opencode/skills/use-jev in your project.

What does Use Jev need to run?

Going by SKILL.md and its folder, Use Jev needs credentials named JEV_API_KEY. Our summary lists: Python 3; A credential in JEV_API_KEY.

Does Use Jev access the network?

SKILL.md names 2 domains. As links in the text: docs.typesafe.ai and typesafe.ai. This is read from the text; nothing was executed.

Is Use Jev safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Use Jev use?

Use Jev is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Use Jev use?

About 806 tokens (SKILL.md is roughly 3.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Use Jev?

Skills that share tags, products or a category with Use Jev: Rust Path Types (openinterpreter/openinterpreter, 69k stars), Python Type Safety (wshobson/agents, 40k stars), Pyrefly Type Coverage (pytorch/pytorch, 104k stars) and Omh Jev Ask (rlaope/oh-my-hermes, 3.2k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Use Jev?

OpenHands (a GitHub organization) maintains it in OpenHands/extensions, which has 157 GitHub stars. The repository holds 78 skills in this directory. The repository was last updated on October 6, 2026.

Source: OpenHands/extensions on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Use Jev

Facts

At a glance

What it does

Example prompts

Requirements

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Choice, Score, and Noul

Files

Compare with similar skills

Similar skills

More from OpenHands/extensions

Questions about Use Jev