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 skills add HermeticOrmus/python-conventions-skills --skill python-conventionsgit clone --depth 1 https://github.com/HermeticOrmus/python-conventions-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/hermeticormus/python-conventions-skills/python-conventions)<a href="https://agentmods.dev/skills/hermeticormus/python-conventions-skills/python-conventions"><img src="https://agentmods.dev/badge/skills/hermeticormus/python-conventions-skills/python-conventions/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/hermeticormus/python-conventions-skills/python-conventions"><img src="https://agentmods.dev/badge/skills/hermeticormus/python-conventions-skills/python-conventions.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00042 | $0.00283 |
| Opus 5.5 | $0.00017 | $0.00113 |
| Sonnet 5.5 | $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 1mo ago.
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.
- 1mo ago 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 4mo ago), licensed MIT. It adds 42 tokens to every session and 283 once invoked, about $0.0002 per session on Opus 5.5. 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.
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