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.
npx agentmods add skills/hermeticormus/python-conventions-skills/python-conventionsnpx skills add HermeticOrmus/python-conventions-skills --skill python-conventionsgit clone --depth 1 https://github.com/HermeticOrmus/python-conventions-skillsWhat 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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00042 | $0.00283 |
| Opus 5 | $0.00021 | $0.00142 |
| Sonnet 5 | $0.00008 | $0.00057 |
| Haiku 4.5 | $0.00004 | $0.00028 |
Grade A, and why
python-conventions scanned grade A with 1 finding 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.
Runs shell commandslowCapability
Expected in a hook, worth knowing in a rule or an instructions file.
- subprocess.run over os.system What it actually says
Python conventions
Modern Python (3.11+) defaults.
Types
- Type hints required everywhere
from __future__ import annotationsat top- Pydantic v2 for I/O, TypedDict for internal, Literal for string enums
Stdlib
- pathlib.Path over os.path
- dataclasses over manual init
- subprocess.run over os.system
- f-strings except logging
- match for tagged unions
Async
- async def end-to-end, httpx not requests
- TaskGroup for structured concurrency
- Never time.sleep in async
Logging
- structlog or stdlib + structured extras
- No print() in libraries
- Lazy formatting
Tooling
- ruff for lint + format
- mypy --strict
- pytest fixtures
- uv over pip
Banned
- Bare except
- Mutable defaults
from foo import *- eval/exec on user input
- Stringly-typed returns
Full content + 15 worked examples at https://github.com/HermeticOrmus/python-conventions-skills.
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.
- yesterday First seen · 55 lines · 42 tokens per session scan A 3bcc33f17120
python-conventions is a skill published in the GitHub repository HermeticOrmus/python-conventions-skills (2 stars, last pushed 3mo ago), licensed MIT. It adds 42 tokens to every session and 283 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 1 finding (runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
Other skills, from other repositories
auth-web-cloudbase
CloudBase Web Authentication Quick Guide for frontend integration after auth-tool has already been checked. Provides concise and practical Web authentication solutions with multiple login methods and complete user management.
fix-codesign-error
Slash command that inspects a macOS signing or entitlement failure and explains the minimum fix path. Invoke explicitly with /fix-codesign-error — this skill never self-triggers.
browse-and-evaluate
Use when exploring the ai-agent-skills catalog to find, compare, and evaluate skills before installing. Always use --fields to limit output size and --dry-run before committing to an install.
specflow-use
To connect Rosetta with Grid Dynamics SpecFlow MCP; only when SpecFlow is mentioned and the MCP is installed.
loop-engineering
Shared loop-engineering reference for COG skills - the agent loop, deterministic verifiers, termination conditions, in-loop context management, and named patterns. Invoke when designing or debugging a skill that iterates (search-verify-retry, scan-until-dry, fetch-retry-gate).
telnyx-messaging-hosted-curl
Set up hosted SMS numbers, toll-free verification, and RCS messaging. Use when migrating numbers or enabling rich messaging features. This skill provides REST API (curl) examples.