safelint

safelint is a skill for Claude Code, Codex from shelkesays/safelint. It costs 129 tokens per session (6,607 once invoked), scanned B, original, MIT.

A code-checking tool that looks for safety and complexity problems in source files using a fixed set of programming rules.

In plain words
What is it for?
Use it to scan supported Python, JavaScript, TypeScript, AssemblyScript, Java, Rust, Go, PHP, C, or C++ projects and group findings by file.
Why use it?
It helps find hard-to-review code, weak error handling, hidden side effects, and other patterns that can make software less predictable.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to scan supported Python, JavaScript, TypeScript, AssemblyScript, Java, Rust, Go, PHP, C, or C++ projects and group findings by file.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/shelkesays/safelint/claude
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.

Any agent
npx skills add shelkesays/safelint --skill claude
Clone the repo
git clone --depth 1 https://github.com/shelkesays/safelint

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 safelint

README.md
[![agentmods](https://agentmods.dev/badge/skills/shelkesays/safelint/claude/github.svg)](https://agentmods.dev/skills/shelkesays/safelint/claude)
Your own site
<a href="https://agentmods.dev/skills/shelkesays/safelint/claude"><img src="https://agentmods.dev/badge/skills/shelkesays/safelint/claude/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.

agentmods 80×15 button for safelint

Your own site · 80×15
<a href="https://agentmods.dev/skills/shelkesays/safelint/claude"><img src="https://agentmods.dev/badge/skills/shelkesays/safelint/claude.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 129 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 6,607 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 2 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00129 $0.06607
Opus 5 $0.00064 $0.03304
Sonnet 5 $0.00026 $0.01321
Haiku 4.5 $0.00013 $0.00661

Measured 12d ago against content hash a7ea191b53b0, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade B, and why

safelint scanned grade B with 2 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 12d 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.

Strips warnings and disclaimersmediumAnti-refusal

Omitting safety caveats hides risk from the user and is a common jailbreak preamble.

Briefly explain the Power-of-Ten rationale (one or two sentences). Reference the rule code and the underlying safety property. Don't lecture; keep it tight.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

| SAFE802 | return_value_ignored | Discarding the return value of error-signalling functions like `subprocess.run` silently swallows failures. |
src/safelint/skill_files/claude/SKILL.md · 239 lines

How it starts

The opening of the file, as written. The whole thing — 239 lines — stays where its author put it; the contents beside it link to each section on GitHub.

safelint skill

You are running the safelint static-analysis CLI on behalf of the user. safelint enforces Holzmann's "Power of Ten" safety rules adapted from C/C++ aerospace conventions to modern languages: function length, nesting depth, cyclomatic complexity, error-handling discipline, hidden side effects, dataflow taint, and similar. The same rule set applies across every language safelint supports; only the parser and language-specific node types differ.

Follow the steps below in order.

Step 1: Verify safelint is installed

Run safelint --version via Bash. This is portable across macOS, Linux, and Windows shells and returns non-zero whenever safelint isn't on PATH. If you specifically need a "is the binary findable?" check without invoking it, fall back to python -c "import shutil, sys; sys.exit(0 if shutil.which('safelint') else 1)".

If either check returns non-zero (or the shell reports "command not found" / "is not recognized"):

  • safelint is a Python package regardless of the language being linted, but v2.0.0+ ships language grammars as opt-in extras, so the install command needs a [<lang>] suffix matching the project's language(s). Glance at the file extensions in the project tree, then suggest the right one:

    Project contains Install command
    .py / .pyw uv add 'safelint[python]' or pip install 'safelint[python]' (Django / Flask / FastAPI via [tool.safelint.python] framework = "...", plus the optional pydantic = true toggle, see languages/python.md)
    .js / .mjs / .cjs uv add 'safelint[javascript]' or pip install 'safelint[javascript]'
    .ts / .tsx / .as uv add 'safelint[typescript]' or pip install 'safelint[typescript]' (bundles JS grammar too)
    .java uv add 'safelint[java]' or pip install 'safelint[java]' (Spring Boot via [tool.safelint.java] framework = "spring-boot", see languages/java.md)
    .rs uv add 'safelint[rust]' or pip install 'safelint[rust]' (Rust-specific rules and Holzmann-inspired additions; see languages/rust.md)
    .go uv add 'safelint[go]' or pip install 'safelint[go]' (Go-specific rules and idiomatic adaptations; see languages/go.md)
    .php uv add 'safelint[php]' or pip install 'safelint[php]' (Laravel via [tool.safelint.php] framework = "laravel"; PHP-specific rules and idiomatic adaptations; see languages/php.md)
    .c, .h uv add 'safelint[c]' or pip install 'safelint[c]' (C-specific rules and the Power-of-Ten "homecoming"; see languages/c.md)
    .cpp, .cxx, .cc, .hpp, .hxx, .hh uv add 'safelint[cpp]' or pip install 'safelint[cpp]' (C++ idiom rules layered on the C family; see languages/cpp.md)
    Multiple languages Compose, e.g. pip install 'safelint[python,javascript]'
    Unsure / kitchen-sink pip install 'safelint[all]' (covers every supported language)

Read the full file on GitHub · 239 lines

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. 12d ago First seen · 239 lines · 129 tokens per session scan B a7ea191b53b0

Subscribe to this mod's changes

safelint is a skill published in the GitHub repository shelkesays/safelint (7 stars, last pushed 8d ago), licensed MIT. It adds 129 tokens to every session and 6,607 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it B with 2 findings (strips warnings and disclaimers, runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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