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/justanesta/claude-code-resources/python-package-developmentnpx skills add justanesta/claude-code-resources --skill python-package-developmentgit clone --depth 1 https://github.com/justanesta/claude-code-resourcesWhat 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 | $0.00051 | $0.00727 |
| Opus 5 | $0.00026 | $0.00364 |
| Sonnet 5 | $0.00010 | $0.00145 |
| Haiku 4.5 | $0.00005 | $0.00073 |
Grade A, and why
python-package-development 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.
How it starts
The opening of the file, as written. The whole thing — 141 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Python Package Development
Modern patterns for building and distributing Python packages.
Modern Package Structure (src layout)
my-package/
├── src/
│ └── mypackage/
│ ├── __init__.py
│ └── core.py
├── tests/
├── docs/
├── pyproject.toml
├── README.md
└── LICENSE
Why src layout?
- Ensures tests run against installed package
- Prevents accidental imports from working directory
- Industry best practice
pyproject.toml Configuration
[build-system]
requires = ["hatchling"]
build-backend = "hatchling.build"
[project]
name = "mypackage"
version = "0.1.0"
description = "A short description"
readme = "README.md"
requires-python = ">=3.10"
dependencies = [
"pandas>=2.0.0",
]
[project.optional-dependencies]
dev = ["pytest>=7.0.0", "black>=23.0.0"]
See pyproject-toml-guide.md for:
- Build backend choices
- Dynamic versioning
- Entry points
Versioning Strategy
Semantic Versioning
MAJOR.MINOR.PATCH
1.0.0 → Initial release
1.0.1 → Bug fix
1.1.0 → New feature
2.0.0 → Breaking change
See versioning-strategies.md for:
- CalVer
- Automatic versioning from git tags
Dependency Management
# Library - use ranges
dependencies = ["requests>=2.31.0"]
# Application - pin versions
dependencies = ["requests==2.31.0"]
See dependency-strategies.md for:
- When to pin vs range
- Upper bounds debate
Testing Packages
# tests/test_core.py
import pytest
from mypackage import main_function
def test_main_function():
result = main_function(input_data)
assert result == expected
See package-testing.md for:
- Integration testing
- Coverage requirements
- CI/CD setup
Documentation
See documentation-guide.md for:
- README essentials
- Docstring styles
- MkDocs/Sphinx
Building and Publishing
# Build
python -m build
# Test on TestPyPI
twine upload --repository testpypi dist/*
# Publish to PyPI
twine upload dist/*
What ships with it
6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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 · 141 lines · 51 tokens per session scan A dbbb5479730f
python-package-development is a skill published in the GitHub repository justanesta/claude-code-resources (2 stars, last pushed 4mo ago), licensed MIT. It adds 51 tokens to every session and 727 once invoked, about $0.0003 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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