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 oborchers/fractional-cto --skill pyproject-tomlgit clone --depth 1 https://github.com/oborchers/fractional-ctoWrote 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/oborchers/fractional-cto/pyproject-toml)<a href="https://agentmods.dev/skills/oborchers/fractional-cto/pyproject-toml"><img src="https://agentmods.dev/badge/skills/oborchers/fractional-cto/pyproject-toml/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/oborchers/fractional-cto/pyproject-toml"><img src="https://agentmods.dev/badge/skills/oborchers/fractional-cto/pyproject-toml.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 | $0.00101 | $0.03008 |
| Opus 5.5 | $0.00040 | $0.01203 |
| Sonnet 5.5 | $0.00020 | $0.00602 |
| Haiku 4.5 | $0.00010 | $0.00301 |
Grade A, and why
pyproject-toml 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 3d 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.
How it starts
The opening of the file, as written. The whole thing — 281 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Configure Everything in pyproject.toml
pyproject.toml is the single source of truth for a Python package: build system, metadata, dependencies, and tool configuration. As of pip 24.0, setup.py install is no longer supported. Every major package -- Pydantic, httpx, Flask, pytest, attrs, Ruff -- has migrated. There is no reason to use setup.py, setup.cfg, or requirements.txt as primary configuration for any new package.
Anatomy: The Four Sections
Every pyproject.toml contains four logical sections. Keep them in this order:
[build-system]-- declares the build backend (PEP 517/518)[project]-- standardized metadata (PEP 621)[dependency-groups]-- dev-only dependencies (PEP 735)[tool.*]-- tool-specific configuration (pytest, mypy, ruff, coverage)
Build Backend Selection
Use hatchling for new pure-Python packages. It is PyPA-maintained, fast, extensible, and the default for hatch new and uv init --lib.
| Your Package | Use This Backend | Declaration |
|---|---|---|
| Pure Python (new) | hatchling | requires = ["hatchling"] |
| Pure Python (very simple) | flit-core | requires = ["flit_core>=3.10,<4"] |
| Pure Python (legacy) | setuptools | requires = ["setuptools>=75.0"] |
| Rust extensions (PyO3) | maturin | requires = ["maturin>=1.7,<2.0"] |
| C/C++ with CMake | scikit-build-core | requires = ["scikit-build-core>=0.10"] |
What top packages use:
| Package | Backend | Reason |
|---|---|---|
| Pydantic, httpx, Black, attrs | hatchling | Modern, clean, PyPA-aligned |
| Flask, Jinja2, Werkzeug | flit-core | Simple, minimal needs |
| pytest | setuptools | Historical, complex build |
| Polars, Ruff, pydantic-core | maturin | Rust (PyO3) bindings |
PEP 621: Project Metadata
Only name and version are strictly required (unless version is listed in dynamic). For any public package, always set these recommended fields:
| Field | Purpose | Example |
|---|---|---|
name |
PyPI distribution name (kebab-case) | "my-library" |
version |
PEP 440 version (or list in dynamic) |
"1.0.0" |
description |
Single-line summary | "A fast HTTP client" |
readme |
PyPI long description | "README.md" |
license |
PEP 639 SPDX expression | "MIT" |
requires-python |
Minimum supported Python | ">=3.10" |
authors |
Author list | [{ name = "Jane Doe" }] |
classifiers |
Trove classifiers (include Typing :: Typed) |
See Reference Configuration |
dependencies |
Runtime dependencies (lower bounds only) | ["httpx>=0.27"] |
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.
- 3d ago First seen · 281 lines · 101 tokens per session scan A 8ab8864298b9
pyproject-toml is a skill published in the GitHub repository oborchers/fractional-cto (32 stars, last pushed 3d ago), licensed MIT. It adds 101 tokens to every session and 3,008 once invoked, about $0.0004 per session on Opus 5.5. 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 2026-10-13.
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