What is Arbitype?

Arbitype is an MCP-native typed decision layer for AI agents, powered by TypeSafe Jev. It turns probabilistic judgments into structured decision primitives that an agent or program can consume directly.

Arbitype is available on PyPI and the official MCP Registry.

[!NOTE] Arbitype is an independent open-source project. It is not an official TypeSafe AI product or an official integration for any particular agent host.

Quick Start

The fastest way to connect an MCP host is a local STDIO server launched by uvx:

export TYPESAFE_API_KEY="your-key"
uvx arbitype

For a pinned, reproducible launch:

uvx --from 'arbitype==0.7.0' arbitype

Or install the package into the current environment:

python -m pip install arbitype
arbitype

The API key stays in the process environment. It is not an MCP argument and is never printed to standard output.

Host setup

Inspect detected hosts before writing anything:

arbitype setup --detect --dry-run

Then apply a reviewed plan:

arbitype setup codex
arbitype doctor --json

The setup flow is plan → unified diff → confirmation → backup → apply. Use claude, cursor, or vscode in place of codex. Detailed host formats, secret forwarding, --yes, --remove, ownership, and non-interactive behavior are documented in docs/HOST_SETUP.md.

Configuration

At minimum, set TYPESAFE_API_KEY. To select a model explicitly:

export TYPESAFE_API_KEY="your-key"
export TYPESAFE_MODEL="jev-latest"

See the full configuration reference for endpoints, timeouts, retries, and request/response limits.

Compatibility

arbitype is the canonical distribution, Python package, and CLI. Existing TypeSafe MCP users should migrate to Arbitype; see docs/REGISTRY_MIGRATION.md.

For the safe migration from the historical distribution:

python -m pip uninstall typesafe-mcp
python -m pip install arbitype

... View full README on GitHub