Jev Judge MCP

An MCP server that gives your coding agent fifteen judgment tools backed by TypeSafe's Jev model. The agent hands a tool some evidence and a question it can enumerate: is this claim supported, is this page safe to read, which of these files answers the question, did this patch finish the task. Jev answers with probabilities, usually in under a second (median 464.6 ms round trip in the recorded bench), for about $0.025 per 1,000 decisions on the recorded classify run — and on that benchmark every answer the policy auto-accepted was correct, with the misses routed to review instead of through. Policy turns the probabilities into one of three actions: auto (proceed), review (check it another way), or escalate (stop). The numbers and their sources: Measured results.

Use it for checks that have a fixed set of answers. When the step needs new text, code, or options you cannot list, the agent should write it itself.

Install

You need Python 3.12+, uv, a POSIX system (Linux or macOS), and a TypeSafe API key from console.typesafe.ai. The published package is on PyPI, and these three commands configure your agents to launch that pinned package (ADR-0051):

# verify your key, then store it
uvx --from 'jev-judge-mcp[typesafe]' jev-judge-mcp setup
# add the server to your agents
uvx --from 'jev-judge-mcp[typesafe]' jev-judge-mcp install
# check the configuration, offline
uvx --from 'jev-judge-mcp[typesafe]' jev-judge-mcp doctor

Every entry the installer writes also requests a Python the package itself declares — --python '>=3.12', taken from the package's Requires-Python metadata (ADR-0053). On a machine whose first interpreter is older (Ubuntu 22.04's 3.10, macOS system 3.9), uv picks or downloads one that qualifies instead of refusing to start the server.

More installer options

To develop against an unreleased tree, install from a clone and pass --from-checkout, which pins the entries at your checkout instead of the PyPI package:

git clone https://github.com/PyModel/jev-judge-mcp
cd jev-judge-mcp
uv sync --extra typesafe
uv run jev-judge-mcp install --from-checkout

That extra is only for running the server. Development and make typecheck need the full sync: uv sync --locked --all-extras — a plain uv sync fails make typecheck with confusing Import "typesafe_sdk" could not be resolved errors.

Running install from an unreleased clone without --from-checkout? It prints a note that the pinned PyPI build does not include your local changes, and points here. The post-write check then exercises the published build, not your tree.

Installed from a clone earlier? One plain re-run of install rewrites the entries this installer owns to the version-pinned PyPI spec — that is the whole migration. Entries the installer does not own are left alone.

Restart your agent. The tools show up as jev_verify, jev_gate, and so on (mcp__jev__* in Claude Code).