Guide · Agent skill
How to use the Python Design Patterns agent skill
Updated · written with AI from the project's own documentation and checked against our catalogue data
The python-design-patterns skill gives an AI agent a set of Python design guidelines to follow when you design, refactor or review code. It is useful for Python developers who need help deciding how to split responsibilities, when to add an abstraction, and when to prefer composition over inheritance. After this guide you will know what the skill does, how to install it from the ZIP download or the Claude apps, and how to ask for its help with natural requests.
Python Design Patternswshobson/agents · MIT Download the skill Quick start
- 1Download the ZIP. Get the python-design-patterns ZIP from the skill page on this site.
- 2Unzip the folder. Extract it so the folder contains SKILL.md and references/details.md.
- 3Place it in a skills folder. Put it in ~/.claude/skills/ for all projects, or in a project's .claude/skills/ for one project.
- 4Or upload in the Claude apps. In the Claude apps, go to Settings → Capabilities → Skills and upload the skill.
- 5Describe your design task. Ask in plain language, such as asking whether a class has too many responsibilities.
- 6Review the suggestions. Read the agent's advice and apply changes yourself, since the skill does not edit files on its own.
What does the python-design-patterns skill make the agent do?
When installed, the agent gets a set of design guidelines for Python code. The core ideas are KISS (keep it simple), Single Responsibility (each unit has one reason to change), Separation of Concerns, composition over inheritance, and the Rule of Three, which says to wait until you have three instances before abstracting duplicated code.
The skill is advice and review guidance. It does not build or run software, and it does not change your files by itself. The agent uses the guidelines to shape its answers and reviews.
- Choose the simplest solution that works, and justify added complexity with concrete requirements.
- Split a class or function when its changes come from different domains, such as HTTP parsing mixed with business rules.
- Prefer combining objects over extending classes.
- Keep layers pointing one way, for example API to Service to Repository.
How do you install the skill?
You can install the skill by downloading the ZIP from the skill page and unzipping it into a skills folder. Use ~/.claude/skills/ to make it available across your projects, or a project's .claude/skills/ folder to limit it to one project.
In the Claude apps, you can instead upload the skill under Settings → Capabilities → Skills.
- Download the ZIP from the skill page on this site.
- Unzip it so the python-design-patterns folder contains SKILL.md and references/details.md.
- Place the folder in ~/.claude/skills/ for personal use, or in a project's .claude/skills/ for one project.
- Or upload it in the Claude apps under Settings → Capabilities → Skills.
How do you trigger the skill with natural requests?
You do not need a special command. Describe the design task in plain language and the agent will use the skill when your request matches its description. The skill is meant for designing a new service or component, refactoring a God class or monolithic function, deciding whether to add an abstraction, reviewing a pull request for tight coupling or leaking internal types, choosing between inheritance and composition, and making code easier to test when I/O and business logic are entangled.
- "Should I split this 400-line class, or is it fine as one?"
- "Review this pull request for tight coupling or layering problems."
- "Do I need a factory here, or is a dictionary enough?"
- "Help me choose between inheritance and composition for these handlers."
What examples does the skill include?
The main guide shows a quick-start example about formatter lookup. Instead of a factory with registration, it suggests a simple dictionary that maps names to formatter classes, with a function that raises a ValueError for unknown names. The supporting reference file expands on this with more patterns and worked examples.
FORMATTERS = {"json": JsonFormatter, "csv": CsvFormatter}
def get_formatter(name: str) -> Formatter:
return FORMATTERS[name]()What does the skill need, and what are the safety notes?
The skill lists no requirements. It does not run scripts and does not use the network, so there is nothing extra to install and no code it executes on your machine. Its files are SKILL.md and references/details.md.
Because it is guidance, you still review any changes the agent suggests before applying them to your code.
- Requires: nothing listed.
- Runs scripts: no.
- Uses network: no.
- Licence: MIT.
What tips help you get the most from it?
Give the agent concrete context: the size of the class, the layers involved and what changes you expect. The skill's troubleshooting notes suggest a practical test for oversized classes: list every change that could require editing the class, and split it if the items come from different domains.
If constructors grow past seven or so parameters, the skill advises splitting the class first rather than dropping dependency injection. If the duplicated copies are already diverging and causing bugs, the Rule of Three can be overridden.
- Use the "reason to change" test on large classes.
- Split classes before reducing constructor parameters.
- Keep composition shallow, roughly two to three levels.
- Pair it with the related skills python-testing-patterns and python-project-structure.
What people use it for
- Deciding how to layer a new Python service into API, service and repository parts.
- Refactoring a large God class by listing its reasons to change and splitting along them.
- Reviewing a pull request for leaking internal types or a service importing from handlers.
- Choosing between a simple dictionary lookup and a factory with registration.
- Making a tangled module easier to test by separating I/O from business logic.
Frequently asked questions
How do I install the python-design-patterns skill?
Download the ZIP from the skill page and unzip it into ~/.claude/skills/ for personal use, or into a project's .claude/skills/ folder. In the Claude apps, you can instead upload it under Settings → Capabilities → Skills.
Is the python-design-patterns skill free?
The skill is licensed under MIT. The source does not list any price, so check the skill page for current details.
Does this skill write code for me?
No. The skill provides design guidance and patterns for the agent to follow. It does not build or run software and does not change files by itself.
What does the skill require to run?
The skill lists no requirements. It does not run scripts and does not use the network.
Can I use it on a non-Python project?
It is not suited to non-Python codebases, because its examples and advice are Python-specific.
What are the alternatives if this skill is not what I need?
If you need a finished program or automated code generation, this skill is not the right fit. For testing or project layout, the related skills python-testing-patterns and python-project-structure cover those topics.
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Our verdict
Choose this skill if you are a Python developer designing a new module, splitting a large class, or reviewing code for coupling and hard-to-test I/O. Skip it if you need code generated or software built, or if your codebase is not in Python, since it only offers guidance and patterns.
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