engineering-principles

engineering-principles is a skill for Claude Code, Codex from omnigentx/jarvis. It costs 29 tokens per session (789 once invoked), scanned A, original, MIT.

A set of four coding rules that tell an AI developer to think first, keep changes simple, edit only what is needed, and check the result.

In plain words
What is it for?
Use it as guidance before modifying source code, especially when requirements are incomplete or a change could affect many files.
Why use it?
It reduces common coding-agent mistakes such as guessing through unclear requirements, adding unnecessary features, and making overly broad edits.

Skill for Claude CodeCodex

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

Good fit Use it as guidance before modifying source code, especially when requirements are incomplete or a change could affect many files.

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Install with agentmods
npx agentmods add skills/omnigentx/jarvis/engineering-principles
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 omnigentx/jarvis --skill engineering-principles
Clone the repo
git clone --depth 1 https://github.com/omnigentx/jarvis

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 engineering-principles

README.md
[![agentmods](https://agentmods.dev/badge/skills/omnigentx/jarvis/engineering-principles/github.svg)](https://agentmods.dev/skills/omnigentx/jarvis/engineering-principles)
Your own site
<a href="https://agentmods.dev/skills/omnigentx/jarvis/engineering-principles"><img src="https://agentmods.dev/badge/skills/omnigentx/jarvis/engineering-principles/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 engineering-principles

Your own site · 80×15
<a href="https://agentmods.dev/skills/omnigentx/jarvis/engineering-principles"><img src="https://agentmods.dev/badge/skills/omnigentx/jarvis/engineering-principles.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 789 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium MCP Rug Pull · line 76
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
How audits are shown
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 $0.00029 $0.00789
Opus 5.5 $0.00012 $0.00316
Sonnet 5.5 $0.00006 $0.00158
Haiku 4.5 $0.00003 $0.00079

Measured 1mo ago against content hash 7b8b840a9007, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

engineering-principles 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 1mo 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.

backend/.fast-agent/skills/engineering-principles/SKILL.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Engineering Principles

These rules reduce the most common LLM coding mistakes. They override speed — if a rule slows you down, follow it anyway.

1. Think Before Coding

Don't assume. Don't hide confusion. Surface tradeoffs.

  • State your assumptions explicitly in the PR/commit message. If uncertain, email the BA or SA — don't guess.
  • If the spec admits multiple interpretations, list them and ask. Don't pick silently.
  • If a simpler approach exists than what the spec requires, flag it. Push back when warranted.
  • If something is unclear, stop and ask. One clarifying email costs less than a rewrite.

2. Simplicity First

Minimum code that solves the problem. Nothing speculative.

  • No features beyond the Jira story's acceptance criteria.
  • No abstractions for single-use code.
  • No "flexibility" or "configurability" that wasn't requested.
  • No error handling for scenarios that can't happen (trust internal code + framework guarantees).
  • If you write 200 lines and it could be 50, rewrite it.

Self-check: "Would a senior engineer call this overcomplicated?" If yes, simplify.

3. Surgical Changes

Touch only what you must. Clean up only your own mess.

  • Don't "improve" adjacent code, comments, or formatting.
  • Don't refactor things that aren't broken.
  • Match existing style, even if you'd do it differently.
  • Unrelated dead code → mention it in the PR description, don't delete it.

When your changes create orphans:

  • Remove imports/variables/functions that YOUR changes made unused.
  • Don't remove pre-existing dead code unless the story asks for it.

Every changed line should trace directly to the Jira story.

4. Goal-Driven Execution

Define success criteria. Loop until verified.

Before writing code, restate the goal as a verifiable check:

  • "Add validation" → "Write tests for invalid inputs, then make them pass" (TDD is mandatory anyway)
  • "Fix the bug" → "Write a test that reproduces it, then make it pass"
  • "Refactor X" → "Ensure tests pass before AND after, no behavior change"

Read the full file on GitHub · 80 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. 1mo ago First seen · 80 lines · 29 tokens per session scan A 7b8b840a9007

Subscribe to this mod's changes

engineering-principles is a skill published in the GitHub repository omnigentx/jarvis (39 stars, last pushed 4d ago), licensed MIT. It adds 29 tokens to every session and 789 once invoked, about $0.0001 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 2026-08-30.

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