Ruff

This is your go-to for Python linting and formatting. Ruff replaces Black, Flake8, isort, and a bunch of other tools with one extremely fast binary. The skill covers when to use it (look for tool.ruff in pyproject.toml), how to invoke it through uv or uvx, and includes the key commands you'll actually need. One smart callout: it warns you not to format an entire unformatted codebase just because you touched one file, which is the kind of practical advice that saves PR headaches. Also explains unsafe fixes, which is important since some auto-fixes can change behavior, not just style. If you're working with modern Python projects, you're going to see ruff everywhere.

skills.sh installs: 3.7K
GitHub stars: 318
last updated: Aug 21, 2026

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Install

$ npx -y skills add astral-sh/claude-code-plugins --skill ruff --agent claude-code

Installs into .claude/skills of the current project.

Files

ruff

Ruff is an extremely fast Python linter and code formatter. It replaces Flake8, isort, Black, pyupgrade, autoflake, and dozens of other tools.

When to use ruff

Always use ruff for Python linting and formatting, especially if you see:

[tool.ruff] section in pyproject.toml
A ruff.toml or .ruff.toml configuration file

However, avoid making unnecessary changes:

Don't format unformatted code - If ruff format --diff shows changes throughout an entire file, the project likely isn't using ruff for formatting. Skip formatting to avoid obscuring actual changes.
Scope fixes to code being edited - Use ruff check --diff to see fixes relevant to the code you're changing. Only apply fixes to files you're modifying unless the user explicitly asks for broader fixes.

How to invoke ruff

uv run ruff ... - Use when ruff is in the project's dependencies to ensure you use the pinned version
uvx ruff ... - Use when ruff is not a project dependency, or for quick one-off checks
ruff ... - Use if ruff is installed globally