Pyproject Toml Validator

Validate Python project pyproject.toml files against PEP 517/621 rules for project metadata, build system, and tool configurations with detailed reports.

Validate pyproject.toml files for Python projects against PEP 517/621 standards.

What it does

Checks your pyproject.toml for common mistakes across three areas:

• [project] — name format (PEP 508), version, license (SPDX), classifiers, dependency specs, authors, dynamic fields
• [build-system] — requires, build-backend validation, known backends
• [tool.*] — ruff, mypy, pytest, black, isort section validation with tool-specific rules

Rules (30+)

Category	Rules	Examples
Project metadata (10)	Missing name/version, invalid name format, unknown fields, malformed requires-python, unknown classifiers, empty authors, name in dynamic	name = "My Package!" → invalid PEP 508 name
Dependencies (4)	Duplicate deps, unpinned deps, overlapping optional groups	requests and Requests both listed
Build system (4)	Missing requires/build-backend, empty requires, unknown fields	No [build-system] table
Tool sections (12+)	Ruff select/ignore overlap, mypy type mismatches, black/ruff conflict, isort/ruff conflict, unusual line lengths, invalid target versions	[tool.ruff.lint] select = ["E501"] + ignore = ["E501"]

Output formats

• text — human-readable with severity icons (❌ ⚠️ ℹ️)
• json — structured with summary counts
• summary — one-line PASS/WARN/FAIL

Exit codes

• 0 — no errors (warnings/info allowed)
• 1 — errors found (or --strict with any issue)
• 2 — file not found or parse error

Commands

validate

Full validation of all sections.

python3 scripts/pyproject_validator.py validate pyproject.toml
python3 scripts/pyproject_validator.py validate --format json pyproject.toml
python3 scripts/pyproject_validator.py validate --strict pyproject.toml

project

Validate only the [project] table.

python3 scripts/pyproject_validator.py project pyproject.toml

build

Validate only [build-system].

python3 scripts/pyproject_validator.py build pyproject.toml

tools

Validate only [tool.*] sections (ruff, mypy, pytest, black, isort).

python3 scripts/pyproject_validator.py tools --min-severity warning pyproject.toml

Options

Option	Values	Default	Description
--format	text, json, summary	text	Output format
--min-severity	error, warning, info	info	Filter by minimum severity
--strict	flag	off	Exit 1 on any issue

Requirements

• Python 3.11+ (uses tomllib from stdlib)
• Falls back to built-in simple TOML parser on Python 3.10

Examples

# Quick check
python3 scripts/pyproject_validator.py validate pyproject.toml

# CI pipeline
python3 scripts/pyproject_validator.py validate --strict --format summary pyproject.toml

# Check only tool configs
python3 scripts/pyproject_validator.py tools --format json pyproject.toml

# Filter noise
python3 scripts/pyproject_validator.py validate --min-severity warning pyproject.toml