using-uv

using-uv is a skill for Claude Code, Codex from lexler/skill-factory. It costs 25 tokens per session (342 once invoked), scanned A, original, Apache-2.0.

A tool for creating Python projects and managing the packages and Python versions they need. It supports both single-file scripts and structured projects with locked dependency versions.

In plain words
What is it for?
Use it to start Python projects, add or run dependencies, execute tests and scripts, and run one-off development tools.
Why use it?
It keeps project setup reproducible, so the same dependencies can be used across machines and by different team members.

Skill for Claude CodeCodex

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 skills/lexler/skill-factory/using-uv
Any agent
npx skills add lexler/skill-factory --skill using-uv
Clone the repo
git clone --depth 1 https://github.com/lexler/skill-factory

Made for: Claude Code, Codex.

Wrote 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.

agentmods badge for using-uv

README.md
[![agentmods](https://agentmods.dev/badge/skills/lexler/skill-factory/using-uv.svg)](https://agentmods.dev/skills/lexler/skill-factory/using-uv)
Your own site
<a href="https://agentmods.dev/skills/lexler/skill-factory/using-uv"><img src="https://agentmods.dev/badge/skills/lexler/skill-factory/using-uv.svg" alt="Measured on agentmods" height="20"></a>
Per session 25 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 342 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 $0.00025 $0.00342
Opus 5 $0.00013 $0.00171
Sonnet 5 $0.00005 $0.00068
Haiku 4.5 $0.00003 $0.00034

Measured 4d ago against content hash d70d890eb88d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

using-uv 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 4d 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.

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.

output_skills/developer-tools/using-uv/SKILL.md · 68 lines

What it actually says

UV

UV is a fast Python package manager. Two modes:

Scripts vs Projects

Use scripts when:

  • Single .py file
  • Quick utility, one-off task
  • No shared dependencies across files

Use projects when:

  • Multiple files, modules, or packages
  • Team collaboration
  • Need reproducible environments
  • Building a library or application

Scripts

Standalone Python files with inline dependencies (PEP 723).

#!/usr/bin/env -S uv run --script
# /// script
# requires-python = ">=3.12"
# dependencies = ["requests", "rich"]
# ///

import requests
from rich import print

Run: uv run script.py

See references/scripts.md for full guide.

Projects

Structured Python with pyproject.toml and lockfile.

uv init myproject
cd myproject
uv add requests
uv run python main.py

Key files:

  • pyproject.toml - metadata and dependencies
  • uv.lock - exact versions for reproducibility
  • .python-version - Python version

See references/projects.md for full guide.

Common Patterns

uv run pytest                     # Run in project env
uv add --dev pytest               # Dev dependency
uvx ruff check .                  # One-off tool execution
uv run --with rich script.py      # Script with ad-hoc dep
Files

What ships with it

2 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.

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. 4d ago First seen · 68 lines · 25 tokens per session scan A d70d890eb88d

Subscribe to this mod's changes

using-uv is a skill published in the GitHub repository lexler/skill-factory (231 stars, last pushed 8d ago), licensed Apache-2.0. It adds 25 tokens to every session and 342 once invoked, about $0.0001 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 2026-08-30.

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