2-python

A set of Python coding rules covering type annotations, error handling, data structures, naming, and formatting.

In plain words
What is it for?
Adding type hints, defining dataclasses and enums, handling specific exceptions, organizing classes and files, and using Ruff with uv for formatting and linting.
Why use it?
It helps make Python code easier to understand, check, and maintain by applying consistent conventions.

Cursor rule for Cursor

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 rules/cmnemoi/cursor-rules/2-python
Clone the repo
git clone --depth 1 https://github.com/cmnemoi/cursor-rules

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 218 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 $0.00000 $0.00218
Opus 5 $0.00000 $0.00109
Sonnet 5 $0.00000 $0.00044
Haiku 4.5 $0.00000 $0.00022

Measured yesterday against content hash 23b130d61b48, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

2-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.

general-rules/.cursor/rules/02-programming-languages/2-python.mdc · 34 lines

What it actually says

Type Annotations:

  • Type every function arguments with type hints
  • Avoid using Any
  • Use Type | None for nullable types, instead of Optional
  • Use dict and list for type hints, instead of typing.List or typing.Dict

Error Handling:

  • Use specific exceptions for error handling
  • Avoid catching broad exceptions like Exception

Code Structure:

  • Use dataclasses for simple data structures
  • Prefer NamedTuple for immutable data structures
  • Put classes, error and enums in their own standalone files
  • Put non-public functions and methods at the bottom of the file
  • Prefix non-public functions and methods by an underscore (_)

Enumerations:

  • Use Enum for enumerations
  • Define enum values explicitly

Linting and Formatting:

  • Follow PEP 8 for code style
  • Use Ruff with uv for formatting and linting

Generics:

  • Use TypeVar for generic types
  • Use descriptive type parameter names
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 · 34 lines · 218 tokens per session scan A 23b130d61b48

Subscribe to this mod's changes

2-python is a cursor rule published in the GitHub repository cmnemoi/cursor-rules (2 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 218 tokens. 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.