clean-code-python

Python coding guidance for writing and reviewing programs in Python, a general-purpose programming language.

In plain words
What is it for?
It is for choosing type hints, data classes, safe exception handling, pathlib paths, context managers, and clear Python expressions.
Why use it?
It helps prevent common mistakes such as mutable default values, swallowed errors, unclosed resources, and unstructured data passed through large dictionaries.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/cassettetapecrackle/claude-starters/clean-code-python
Any agent
npx skills add CassetteTapeCrackle/claude-starters --skill clean-code-python
Clone the repo
git clone --depth 1 https://github.com/CassetteTapeCrackle/claude-starters

Made for: Claude Code, Codex.

Per session 39 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 312 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00039 $0.00312
Opus 5 $0.00019 $0.00156
Sonnet 5 $0.00008 $0.00062
Haiku 4.5 $0.00004 $0.00031

Measured yesterday against content hash c242f572097a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

clean-code-python scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/clean-code-python/SKILL.md · 28 lines

What it actually says

Clean-code Python (depth)

On top of the base rules (type hints, ruff, pytest).

Types & data

  • Explicit hints on public functions; from __future__ import annotations for forward refs. No bare Any.
  • Model records with @dataclass (or pydantic at boundaries); avoid dicts-as-objects for structured data.

Footguns

  • Never mutable default args (def f(x=[])) — use None + assign inside.
  • EAFP over LBYL: try/except around the operation rather than pre-checking, but keep try bodies small.
  • No bare except: — catch specific exceptions; re-raise with context.

Idioms

  • pathlib.Path over os.path string surgery. Context managers (with) for files/locks/resources.
  • Comprehensions/generators over manual accumulation loops; generators for large/streamed data.
  • f-strings for formatting; logging not print for diagnostics.

Smells

  • A function taking/returning big untyped dicts → dataclass.
  • except Exception: pass → swallows bugs.
  • Manual file open/close without with → leak on error.
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 28 lines · 39 tokens per session scan A c242f572097a

Subscribe to this mod's changes

clean-code-python is a skill published in the GitHub repository CassetteTapeCrackle/claude-starters (1 stars, last pushed 13d ago), licensed MIT. It adds 39 tokens to every session and 312 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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