flake8-annotations-complexity

An extension for flake8 to report on too complex type annotations.

Complex type annotations often means bad annotations usage, wrong code decomposition or improper data structure choice. They are also hard to read and make code look java-like.

Annotation complexity is maximum annotation nesting level. So List[int] complexity is 2 and Tuple[List[Optional[str]], int] is 4.

The plugin checks annotations of every argument kind (positional-only, regular, *args, keyword-only and **kwargs), return types of both regular and async functions, and annotated assignments.

Checks

Requirements

Python 3.10 – 3.14.

Installation

pip install flake8-annotations-complexity

Example

Sample file:

# test.py


def foo() -> List[int]:
    return [1]

Usage:

$ flake8 --max-annotations-complexity=1 test.py
test.py:4:14: TAE002 too complex annotation (2 > 1)

Contributing

We would love you to contribute to our project. It's simple:

1. Create an issue with bug you found or proposal you have. Wait for approve from maintainer.
2. Create a pull request. Make sure all checks are green.
3. Fix review comments if any.
4. Be awesome.

Here are useful tips:

• The project uses uv. Run make install (or uv sync) to create the environment.
• Install the git hooks once with uv run pre-commit install.
• You can run all checks and tests with make check. Please do it before CI does.
• We use BestDoctor python styleguide.
• We respect Django CoC. Make soft, not bullshit.