Getting it into your agent
It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.
git clone --depth 1 https://github.com/joao-aires/agent-skills-publicnpx agentmods add skills/joao-aires/agent-skills-public/modern-pythonWrote 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/joao-aires/agent-skills-public/modern-python)<a href="https://agentmods.dev/skills/joao-aires/agent-skills-public/modern-python"><img src="https://agentmods.dev/badge/skills/joao-aires/agent-skills-public/modern-python/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/joao-aires/agent-skills-public/modern-python"><img src="https://agentmods.dev/badge/skills/joao-aires/agent-skills-public/modern-python.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 | $0.00039 | $0.02658 |
| Opus 5.5 | $0.00016 | $0.01063 |
| Sonnet 5.5 | $0.00008 | $0.00532 |
| Haiku 4.5 | $0.00004 | $0.00266 |
Grade A, and why
modern-python 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.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
uv run --with requests python -c "import requests; print(requests.get('https://httpbin.org/ip').json())" This is a copy
100% identical to modern-python — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 334 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Modern Python
Guide for modern Python tooling and best practices, based on trailofbits/cookiecutter-python.
When to Use This Skill
- Creating a new Python project or package
- Setting up
pyproject.tomlconfiguration - Configuring development tools (linting, formatting, testing)
- Writing Python scripts with external dependencies
- Migrating from legacy tools (when user requests it)
When NOT to Use This Skill
- User wants to keep legacy tooling: Respect existing workflows if explicitly requested
- Python < 3.11 required: These tools target modern Python
- Non-Python projects: Mixed codebases where Python isn't primary
Anti-Patterns to Avoid
| Avoid | Use Instead |
|---|---|
[tool.ty] python-version |
[tool.ty.environment] python-version |
uv pip install |
uv add and uv sync |
| Editing pyproject.toml manually to add deps | uv add <pkg> / uv remove <pkg> |
hatchling build backend |
uv_build (simpler, sufficient for most cases) |
| Poetry | uv (faster, simpler, better ecosystem integration) |
| requirements.txt | PEP 723 for scripts, pyproject.toml for projects |
| mypy / pyright | ty (faster, from Astral team) |
[project.optional-dependencies] for dev tools |
[dependency-groups] (PEP 735) |
Manual virtualenv activation (source .venv/bin/activate) |
uv run <cmd> |
| pre-commit | prek (faster, no Python runtime needed) |
Key principles:
- Always use
uv addanduv removeto manage dependencies - Never manually activate or manage virtual environments—use
uv runfor all commands - Use
[dependency-groups]for dev/test/docs dependencies, not[project.optional-dependencies]
Decision Tree
What are you doing?
│
├─ Single-file script with dependencies?
│ └─ Use PEP 723 inline metadata (./references/pep723-scripts.md)
│
├─ New multi-file project (not distributed)?
│ └─ Minimal uv setup (see Quick Start below)
│
├─ New reusable package/library?
│ └─ Full project setup (see Full Setup below)
│
└─ Migrating existing project?
└─ See Migration Guide below
What ships with it
14 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.
- agents/openai.yaml 226 B
- assets/trail-of-bits-mark.svg 3.0 KB
- references/dependabot.md 1.8 KB
- references/migration-checklist.md 3.0 KB
- references/pep723-scripts.md 5.0 KB
- references/prek.md 5.8 KB
- references/pyproject.md 5.6 KB
- references/ruff-config.md 5.3 KB
- references/security-setup.md 6.4 KB
- references/testing.md 5.1 KB
- references/uv-commands.md 4.5 KB
- templates/dependabot.yml 958 B
- templates/pre-commit-config.yaml 2.2 KB
- UPSTREAM-LICENSE.txt 20 KB
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 · 334 lines · 39 tokens per session scan A ef774b925eb1
modern-python is a skill published in the GitHub repository joao-aires/agent-skills-public (2 stars, last pushed yesterday), licensed MIT. It adds 39 tokens to every session and 2,658 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). It is 100% identical to modern-python, differing in 0 lines, and is treated as a copy.
Other skills, from other repositories
temporal-python-testing
Test Temporal workflows with pytest, time-skipping, and mocking strategies. Covers unit testing, integration testing, replay testing, and local development setup. Use when implementing Temporal workflow tests or debugging test failures.
test-corpus
The testdocuments submodule is a bucket-fetched fixture corpus that is not committed. This skill covers readtestfixture, missing fixtures, valid A/B controls, and submodule push order. Load before running Rust tests on a fresh clone, setting up an A/B control, adding a fixture-backed test, or diagnosing…
python-providers
Create, modify, test, or package Python provider adapters under python/providers, including framework-specific dependencies, public imports, type inference, and provider metadata. Use for Python provider work only; use python-sdk for core SDK changes.
adk-verify-snippets
Checks that every Python code block in a Markdown file actually compiles and runs, by extracting each block to a temporary file, executing it in an isolated subprocess, and writing a pass/fail report with per-snippet coverage. Use when the user asks to verify, test, or validate the code samples in a README, a guide…
adk-setup
Sets up a local ADK Python development environment in a git clone of the open-source adk-python repository: a uv virtual environment, all dependency extras, pre-commit hooks, and a first unit-test run. Runs only when explicitly requested, never on its own. Use when asked to set up, bootstrap, or repair a development…
test-generator
Generate pytest test cases for Python functions and classes.