The MyPy Python type checker (

Backend: pants.backend.python.typecheck.mypy
Config section: [mypy]

Basic options


default: False

Don't use MyPy when running ./pants check.


--mypy-args="[<shell_str>, <shell_str>, ...]"
default: []

Arguments to pass directly to MyPy, e.g. --mypy-args='--python-version 3.7 --disallow-any-expr'.


default: True

If true, export a virtual environment with MyPy when running ./pants export.

This can be useful, for example, with IDE integrations to point your editor to the tool's binary.

Advanced options


default: mypy==0.910

Requirement string for the tool.


--mypy-extra-requirements="['<str>', '<str>', ...]"
default: []

Any additional requirement strings to use with the tool. This is useful if the tool allows you to install plugins or if you need to constrain a dependency to a certain version.


--mypy-interpreter-constraints="['<str>', '<str>', ...]"

Python interpreter constraints for this tool.


default: <default>

Path to a lockfile used for installing the tool.

Set to the string <default> to use a lockfile provided by Pants, so long as you have not changed the --version and --extra-requirements options, and the tool's interpreter constraints are compatible with the default. Pants will error or warn if the lockfile is not compatible (controlled by [python].invalid_lockfile_behavior). See for the default lockfile contents.

Set to the string <none> to opt out of using a lockfile. We do not recommend this, though, as lockfiles are essential for reproducible builds.

To use a custom lockfile, set this option to a file path relative to the build root, then run ./pants generate-lockfiles --resolve=mypy.

As explained at Third-party dependencies, lockfile generation via generate-lockfiles does not always work and you may want to manually generate the lockfile. You will want to set [python].invalid_lockfile_behavior = 'ignore' so that Pants does not complain about missing lockfile headers.


default: mypy

The console script for the tool. Using this option is generally preferable to (and mutually exclusive with) specifying an --entry-point since console script names have a higher expectation of staying stable across releases of the tool. Usually, you will not want to change this from the default.


default: None

The entry point for the tool. Generally you only want to use this option if the tool does not offer a --console-script (which this option is mutually exclusive with). Usually, you will not want to change this from the default.


default: None

Path to a config file understood by MyPy (

Setting this option will disable [mypy].config_discovery. Use this option if the config is located in a non-standard location.


default: True

If true, Pants will include any relevant config files during runs (mypy.ini, .mypy.ini, and setup.cfg).

Use [mypy].config instead if your config is in a non-standard location.


--mypy-source-plugins="[<target_option>, <target_option>, ...]"
default: []

An optional list of python_sources target addresses to load first-party plugins.

You must also set plugins = in your mypy.ini, and set the [mypy].config option in your pants.toml.

To instead load third-party plugins, set the option [mypy].extra_requirements and set the plugins option in mypy.ini. Tip: it's often helpful to define a dedicated 'resolve' via [python].resolves for your MyPy plugins such as 'mypy-plugins' so that the third-party requirements used by your plugin, like mypy, do not mix with the rest of your project. Read that option's help message for more info on resolves.


--mypy-extra-type-stubs="['<str>', '<str>', ...]"
default: []

Extra type stub requirements to install when running MyPy.

Normally, type stubs can be installed as typical requirements, such as putting them in requirements.txt or using a python_requirement target. Alternatively, you can use this option so that the dependencies are solely used when running MyPy and are not runtime dependencies.

Expects a list of pip-style requirement strings, like ['types-requests==2.25.9'].

Deprecated options