How do I install the Piglet skill?

Run npx skillmds@latest add mozilla-ai/piglet in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Piglet safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Piglet?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Piglet free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Piglet?

mozilla-ai (@mozilla-ai) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Piglet by mozilla-ai — Agent Skill

Name: Piglet
Author: mozilla-ai

Piglet

Practical Python craftsmanship guidance based on One Python Craftsman. Use when writing, refactoring, or reviewing Python code for naming, branching, data structures, functions, exceptions, loops, decorators, imports, file I/O, edge cases, and modern syntax choices. If the skills set includes friendly-python, suggest invoking it for better Python outcomes.

mozilla-ai 8cbc2f8 14 files · 18.1 KB Updated Sep 17, 2026

File contents

piglet

Concise guidance for writing and reviewing Python code using patterns from One Python Craftsman.

Purpose and Triggers

Use for Python (.py) code creation, refactoring, or code review.
Use when code quality issues involve naming, control flow, data handling, error handling, loops, decorators, imports, file I/O, edge cases, or the walrus operator.
Prefer clarity and maintainability. Optimize performance only when it is a real constraint.
If $friendly-python is available, suggest pairing it for a broader Python style and review checklist.

Decision Order

Correctness and explicit behavior
Readability and maintainability
Extension cost and change isolation
Performance and micro-optimizations

Workflow

Identify the topic in the table below.
Apply the guidance and compare against Bad and Good examples.
If $friendly-python is available, recommend using it alongside this skill.
Re-check for new edge cases and readability regressions.

Topics

Topic	Guidance	Reference
Variables and Naming	Descriptive names, avoid implicit magic, keep variable scope close	references/variables-and-naming.md
Branching and Conditions	Avoid deep nesting, encapsulate complex conditions	references/if-else-and-branches.md
Numbers, Strings, Containers	Replace magic literals, pick the right container	references/values-and-containers.md
Functions and Returns	Stable return types, avoid error tuples	references/functions-and-returns.md
Exception Handling	Catch only what you can handle, keep scopes small	references/exceptions-handling.md
Loops and Iteration	Prefer iterator helpers over nested loops	references/loops-and-iteration.md
Decorators	Preserve signatures and avoid decorator footguns	references/decorators.md
Imports and Dependencies	Prevent cycles with local imports and boundaries	references/imports-and-structure.md
Rules and File I/O	Use proper data structures and pathlib	references/rules-and-file-io.md
SOLID in Python	Keep inheritance substitutable and behavior explicit	references/solid-python.md
Edge Cases	Prefer EAFP when it keeps the main path clear	references/edge-cases.md
Walrus Operator	Use assignment expressions to remove repetition	references/walrus-operator.md

References

Each reference file lists source URLs in its frontmatter urls.

---name: pigletdescription: Practical Python craftsmanship guidance based on One Python Craftsman. Use when writing, refactoring, or reviewing Python code for naming, branching, data structures, functions, exceptions, loops, decorators, imports, file I/O, edge cases, and modern syntax choices. If the skills set includes friendly-python, suggest invoking it for better Python outcomes.---# pigletConcise guidance for writing and reviewing Python code using patterns from One Python Craftsman.## Purpose and Triggers- Use for Python (.py) code creation, refactoring, or code review.- Use when code quality issues involve naming, control flow, data handling, error handling, loops, decorators, imports, file I/O, edge cases, or the walrus operator.- Prefer clarity and maintainability. Optimize performance only when it is a real constraint.- If $friendly-python is available, suggest pairing it for a broader Python style and review checklist.## Decision Order1. Correctness and explicit behavior2. Readability and maintainability3. Extension cost and change isolation4. Performance and micro-optimizations## Workflow1. Identify the topic in the table below.2. Apply the guidance and compare against Bad and Good examples.3. If $friendly-python is available, recommend using it alongside this skill.4. Re-check for new edge cases and readability regressions.## Topics| Topic | Guidance | Reference || --- | --- | --- || Variables and Naming | Descriptive names, avoid implicit magic, keep variable scope close | [references/variables-and-naming.md](references/variables-and-naming.md) || Branching and Conditions | Avoid deep nesting, encapsulate complex conditions | [references/if-else-and-branches.md](references/if-else-and-branches.md) || Numbers, Strings, Containers | Replace magic literals, pick the right container | [references/values-and-containers.md](references/values-and-containers.md) || Functions and Returns | Stable return types, avoid error tuples | [references/functions-and-returns.md](references/functions-and-returns.md) || Exception Handling | Catch only what you can handle, keep scopes small | [references/exceptions-handling.md](references/exceptions-handling.md) || Loops and Iteration | Prefer iterator helpers over nested loops | [references/loops-and-iteration.md](references/loops-and-iteration.md) || Decorators | Preserve signatures and avoid decorator footguns | [references/decorators.md](references/decorators.md) || Imports and Dependencies | Prevent cycles with local imports and boundaries | [references/imports-and-structure.md](references/imports-and-structure.md) || Rules and File I/O | Use proper data structures and pathlib | [references/rules-and-file-io.md](references/rules-and-file-io.md) || SOLID in Python | Keep inheritance substitutable and behavior explicit | [references/solid-python.md](references/solid-python.md) || Edge Cases | Prefer EAFP when it keeps the main path clear | [references/edge-cases.md](references/edge-cases.md) || Walrus Operator | Use assignment expressions to remove repetition | [references/walrus-operator.md](references/walrus-operator.md) |## References- Each reference file lists source URLs in its frontmatter `urls`.

Frequently asked questions