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@clacke ?
My favorite starting point is:
```toml
[tool.mypy]
strict = true
show_error_codes = true
show_column_numbers = true
show_error_context = true
```

Some options in `pyproject.toml` started to work in later / more recent versions for me. E.g. `--strict` did not work for me ~ 1yr ago, but it does now.