Spec Driven Development
MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.
Description from the maker (original English)
Local 2B and 0.8B decision models: calibrated yes/no, choice and score answers for your agent.
These three are never merged into one score: opinions, measurements and popularity are different things.
We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.
Pick the AI app you use, then copy the settings.
JEV_STYLE_URLYou need
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Open Claude Desktop → Settings → Developer → Edit Config, and paste this into claude_desktop_config.json
{
"mcpServers": {
"jev-style": {
"command": "uvx",
"args": [
"jev-style",
"mcp"
],
"env": {
"JEV_STYLE_URL": "your-value"
}
}
}
}Run this in your terminal
claude mcp add jev-style --env JEV_STYLE_URL=your-value -- uvx jev-style mcpFill in the empty values before running it.
Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json
{
"mcpServers": {
"jev-style": {
"command": "uvx",
"args": [
"jev-style",
"mcp"
],
"env": {
"JEV_STYLE_URL": "your-value"
}
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
Paste into .vscode/mcp.json in your project
{
"servers": {
"jev-style": {
"type": "stdio",
"command": "uvx",
"args": [
"jev-style",
"mcp"
],
"env": {
"JEV_STYLE_URL": "your-value"
}
}
}
}Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.
This one runs on your computer, and ChatGPT can only connect to servers on the internet. Pick another app.
Your choice stays on this device in a cookie; no account needed.
JEV_STYLE_URL envThese settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.
Runs on your computer; the tool list appears in your AI app after you install it.
We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 7, 2026
The registry name was verified with the GitHub account lawrence3699, which owns the repo
We have not read this repo from GitHub yet
We have not read this repo from GitHub yet
This one runs on your computer; there is no internet endpoint
Runs on your computer and uses local settings instead
Runs on your computer; we can only read tool lists from internet endpoints
Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.
It passed 1 of 1 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.
The registry does not list a required key, though some servers ask you to sign in on first use.
It runs on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).
The GitHub repo last changed –, and the latest version (0.6.3) reached the registry 5 days ago.
Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Python (uv) on your computer.
In the same category: Spec Driven Development, Remote Desktop Commander, First Sale Scout
Servers in the same category from other makers, sorted by stars.
Reading a card:★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi
MCP Server that facilitates spec-driven development workflows, not just Vibe Coding.
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Jev-Style
Small decision models that run on your own machine. Text and images in, a calibrated probability for every option out.
Website · Models · Live demo · PyPI · Agent skills · MCP · Changelog · 简体中文
Created and maintained by Chaoliang Yan . An independent project, not affiliated with TypeSafe or Jev ( details ).
Jev-Style is a family of small decision models (0.8B and 2B, fine-tuned from Qwen3.5) and the toolkit that puts them to work. Give a model text or JSON, optional images and typed questions. It reads the input once and returns a calibrated probability for every option, in one forward pass, on your laptop. Use it to route support tickets to the right team, pick the tool or model an agent should call, tag topics, flag phishing, check receipts and screenshots, or let a coding agent's tool calls through only when a local model agrees. No GPU, no API key and no training needed.
Try it first with nothing installed: the 2B Space runs Jev-Style-2B-Decision-v4 (text and images) and the 0.8B Space runs the 0.8B.
Locally, you need Python 3.10 or newer. In a virtual environment, install one backend for your machine:
pip install -U "jev-style[mlx]" # Apple silicon (text)
pip install -U "jev-style[torch]" # NVIDIA GPU, CPU or image input; Intel Macs, Linux and Windows (also works on Apple MPS)
The bare pip install jev-style installs only the HTTP client, the fake engine and the MCP server; running a model needs one of the extras above. [mlx] pins mlx-lm to 0.31.3 on purpose (the 2B MLX runtimes check the mlx-lm source they patch and refuse any other version), so give jev-style its own virtual environment, or use uv tool install, if other MLX tools in the same environment need a newer mlx-lm.
Start the server and open the local Playground. The first start downloads the 0.8B weights (about 1.5 GB); later starts reuse them.
jev-style serve # add --release 2b for the 2B v4 (images need --backend torch)
In a second terminal, make one decision:
jev-style decide "I was charged twice" --url http://127.0.0.1:8765 --choice "Which team?::billing,shipping,returns"
Or from Python, in one line (loads the model in-process, or uses the server in JEV_STYLE_URL):
import jev_style
jev_style.classify("Where is my parcel? It was due Monday.", ["billing", "shipping", "tech"])
The server speaks the public POST /v1/systemone request shape, so clients written for Jev-compatible servers, including the official SDKs, can point at http://127.0.0.1:8765 with any API key string. For the command line tool on its own: uv tool install "jev-style[all]" on Apple silicon, uv tool install "jev-style[torch]" elsewhere.
noul), multiple choice (choice, up to 255 options) and ordered ratings (score, 2 to 10 levels). The model reads the text once and answers every question about it.assets the way TypeSafe's API takes them. The PyTorch build reads them; the MLX and GGUF builds read text only.jev-style eval scores your own labelled data; every benchmark number here links to a model card with its protocol and confidence intervals.Start with the default 0.8B to try things: 1.5 GB, fast on a laptop. Move to the 2B v4 for accuracy, images and 32,768-token inputs. --release 2b loads the v4; --release 2b-v3 keeps the previous 2B.
Release (--release) | Parameters · smallest build | JevBench v1.4.1 public (231) | tweet_topic, zero-shot (1,693) | Context |
|---|---|---|---|---|
Jev-Style-2B-Decision-v4 (2b) | 2.2B · 1.27 GB (Q4_K_M, text) | 74.9 % | not run | 32,768 tokens, images |
Jev-Style-2B-Decision-v3 (2b-v3) | 1.9B · 1.27 GB (Q4_K_M) | 73.6 % | 82.2 % | 25,600 tokens |
Jev-Style-0.8B-Decision-v3 (0.8b, default) | 0.8B · 0.53 GB (Q4_K_M) | 64.1 % | 75.5 % | 25,600 tokens |
| Hosted Jev 1.13, for reference | – | 86.6 % | 79.3 % | – |
Decision Index. Since 2026-11-04 the 2B v4 is listed on the public Decision Index 0.3 board as jev-style-2b-v4, replacing the 2B v3 entry (34.05): Public 44.37, Full 34.53, Breadth 41.75, and on the Vision board Public 57.55 / Full 51.94. The 0.8B v3 is on the same board at Public 17.0 / Full 12.5. The Full score also counts the maintainers' private test sets, which is why it is lower than the Public score.
How to read the JevBench numbers. The 2B v4 JevBench score is one self-run with the official harness through this package's server (float32, Apple MPS; 95 % CI 68.9 to 80.0 %), not a JevBench board entry. Several benchmarks' official train splits are in the 2B v4's training data, so those results are not zero-shot. The 2B v3 numbers are single pre-declared runs with its GGUF F16 build: on JevBench it is the highest among the Qwen3.5-2B-family systems on the v1.4.1 board (decider-2b 71.0 %, open-jev-zefan-2b 64.5 %), but the lead over decider-2b is inside the 95 % confidence interval, 42 of the 82 board systems score higher, and hosted Jev is well ahead. Each model card gives every protocol: 2B v4, 2B v3, 0.8B v3.
The 0.8B against Laya, on sets neither was trained on
| Model | Banking77 (77 intents, never trained) | MASSIVE intent, 37 held-out languages | tweet_topic, zero-shot | JevBench v1.4.1 public (231) |
|---|---|---|---|---|
| Jev-Style-0.8B-Decision-v3 | 68.2 % | 65.5 % | 75.5 % | 64.1 % |
| Best official Laya checkpoint (0.8B, 1,024 tokens by default) | 49.2 % | 36.1 % | 63.2 % | 58.4 % |
From the 0.8B model card, which gives the full protocol and confidence intervals. The Laya rows are its official checkpoints re-run on the same rows, except tweet_topic and JevBench, which use published numbers. The hosted Jev API has higher accuracy than the 0.8B on every one of these sets where its accuracy is published. On tweet_topic the 2B v3's accuracy is above Jev's published number, but its macro-F1 is below (0.678 vs 0.694).
Every build and its size
| Build | 2B v4 | 2B v3 | 0.8B | Used by |
|---|---|---|---|---|
| safetensors: 2B v4, 2B v3, 0.8B | 4.43 GB | 3.76 GB | 1.50 GB | --backend torch (CUDA, Apple MPS, CPU); the 2B v4 reads images here |
| MLX bf16 / 8-bit: 2B v4, 2B v3, 0.8B | 3.76 / 2.00 GB | 3.76 / 2.00 GB | 1.50 / 0.80 GB | --backend mlx (Apple silicon; auto picks it there) |
| GGUF F16 / Q8_0 / Q4_K_M: 2B v4, 2B v3, 0.8B | 3.78 / 2.01 / 1.27 GB | 3.78 / 2.01 / 1.27 GB | 1.52 / 0.81 / 0.53 GB | --backend gguf (llama.cpp through the release's scorer: jev-score-v2 for both 2Bs, jev-score for the 0.8B) |
These are weight-file sizes, not RAM or VRAM requirements. Each build carries its own runtime file next to the weights; the server downloads a pinned revision a
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