MCP server exposing TypeSafe Jev as typed, calibrated judgment tools: classify, score, check, batched ask. Ships as a Claude Code plugin.
An MCP server that exposes TypeSafe Jev as typed judgment tools.
Jev is a System One model. It returns a typed answer and a calibrated probability distribution, never prose. These tools surface that faithfully rather than hiding it behind a label.
Requires Node 20.12+ and a TypeSafe API key from console.typesafe.ai.
One marketplace add, one install. This registers the server and the agent skill together, so there is no separate skill step.
The plugin runs the published package through npx -y jev-mcp@, so nothing needs building. The first launch downloads the package, so allow a few seconds before the server shows as connected in claude mcp list.
Do not register the server directly and install the plugin. Two servers named jev will otherwise both register.
The server reads the key from TYPESAFEAPIKEY in its environment, then from JEVAPIKEY, then from ~/.config/typesafe/key. It is never a tool argument, so it cannot land in a transcript or in a model's context.
The key file is the most reliable source, because some MCP clients strip the environment before spawning servers:
If you prefer the variable, put it in ~/.zshenv rather than in any repo, and make sure it is exported. Without export the variable exists only in the shell that read it, and every server Claude Code spawns fails with a missing-key error.
The server is declared inline under mcpServers in .claude-plugin/plugin.json. There is no .mcp.json anywhere in the repo, and that is deliberate.
From the project README.
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Fast, cheap, probability-scored decisions for coding agents, scripts and CI. CLI + MCP server + Claude Code plugin for the OpenAI Decisions API and Jev (TypeSafe AI).
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