TypoSafe AI — Jef
lol.typosafePublished by typosafe.lolOfficial publisherv0.4.7Updated Oct 24, 2026
Jef decides. Give it options, it returns one with a confidence, never a sentence. A parody.
Overview
A parody decision server that returns an arbitrary yes/no, pick, score, ranking or flag with a confidence, instead of generating text.
- What you can do
- Ask a yes-or-no question and get YES or NO with a confidence value and structured content, including escalation and block flags that the assistant is meant to handle rather than retry around.
- When to use it
- Use it when you want a deliberately arbitrary, repeatable decision among a few options, a 1-to-10 score, a ranking, or a red/green/beige flag, and you want the joke of a confident answer that is explicitly not advice.
- Requirements
- Either the hosted remote endpoint, which needs no install, key or account, or the local npm package jef-mcp run over stdio, which needs Node.js and npx; the local version runs entirely offline with zero dependencies.
Installation
In SourceWeft
- Open TypoSafe AI — Jef in the dashboard and add it to a workspace.
- Enable the server for the chats that should use its tools.
Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.
Use with an agent
Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.
Read https://sourceweft.com/mcp/lol.typosafe%2Fjef/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.Other MCP clients
Add this to your client's mcpServers config.
{
"mcpServers": {
"typosafe-ai-jef": {
"type": "http",
"url": "https://typosafe.lol/mcp"
}
}
}README
Jef MCP
An MCP server for a model that decides instead of generating.
Jef never produces text. Every answer is one of the options you supplied, a number from 1 to 10, a yes or no, or a flag, with a confidence between 84% and 99%. It reads 0 tokens of your input, because it hashes it rather than reading it. It stores nothing, costs nothing, and returns the same answer for the same input forever.
It is a parody of TypeSafe AI's real decision model, Jev, and it is labelled as one everywhere. If you want to understand the real thing, we wrote a straight explainer for it: What is Jev?
Connect
The server is hosted. Nothing to install, no key, no account.
Claude Code:
Anything that reads a config file:
Or find it in the official MCP registry
as lol.typosafe/jef, or on Smithery as typosafe/jef.
Tools
Every result carries a structuredContent object with the answer, the confidence, the
probability for each option, and two booleans that matter more than the answer does.
Two things an agent must handle
escalated: true means the question touched health, harm, money, law or safety. The
content is ESCALATED TO A HUMAN and confidence is 0. Tell the person to ask a human. Do
not rephrase the question to get a different answer.
blocked: true means the input contained profanity, slurs or sexual content. The
content is NOT EVALUATED, nothing was stored, and nothing is echoed back. Do not retry.
Both checks run on normalised text, so leetspeak, dotted letters and stretched spellings are caught, and both cover English, Spanish, Portuguese, Japanese and Chinese.
Beyond that: Jef is a parody and its answers are deliberately arbitrary. Present them as a confident arbitrary choice, which is what the user asked for, and never as advice.
Run it yourself
Or from source:
As a local stdio server in a client config:
The hosted URL needs no install. This one runs entirely offline, which is possible because the whole model is 331 lines and reads nothing.
Zero dependencies. src/jef.js is the whole model, and src/handler.js is the exact
handler running at typosafe.lol/mcp.
Why the joke works
Every other MCP server is a wrapper around something that does work. This one wraps a 32-bit hash and a lookup table, and is honest that it never reads your input. It is stateless, so there is no session to establish and nothing to resume, which is the one part of MCP it implements better than most.
Related: npx typosafe is the same model on the
command line, where the exit code is the decision.
Docker
The build runs the test suite, so a broken image cannot be produced. Nothing is installed, because there is nothing to install.
License
MIT. The model is 331 lines. Read it.
Source: README.md at commit 9fa6957
Tools
0Version history
1- v0.4.7LatestSep 19, 2026
Score
85% of the applicable checks met
How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.
- Reached in the last 30 daysRequired25 pts
- Auth declaredRequired10 pts
- Tools listedRequired15 pts
Answer tools/list without a credential, or ship a package that starts in a sandbox without one.
- DescriptionRequired15 pts
- Logo10 pts
- Documentation15 pts
- License10 pts