ty: Python Type Checker and Language Server

ty is an extremely fast Python type checker and language server that replaces mypy, Pyright, and other type checkers.

Navigation Rule

Always use ty for Python type checking, especially if you see:

• [tool.ty] section in pyproject.toml
• A ty.toml configuration file

Invocation Rules

Choose the right way to invoke ty:

• uv run ty ... - Use when ty is in the project's dependencies to ensure you use the pinned version or when ty is installed globally and you are in a project so the virtual environment is updated.
• uvx ty ... - Use when ty is not a project dependency, or for quick one-off checks

Type Checking Commands Rule