skill-opt-lite

skill-opt-lite is a skill for Claude Code, Codex from rexleimo/aios. It costs 79 tokens per session (1,687 once invoked), scanned A, original, MIT.

A method for improving skill instruction documents through repeated task runs, failure analysis, edits, and validation. TDD-like training means testing changes against defined tasks rather than relying on intuition.

In plain words
What is it for?
Use it to create or systematically improve skills when you have a task set with outcomes that can be checked objectively.
Why use it?
It helps determine whether an instruction change actually improves results instead of fixing one example while causing new failures.

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/rexleimo/aios/skill-opt-lite
Any agent
npx skills add rexleimo/aios --skill skill-opt-lite
Clone the repo
git clone --depth 1 https://github.com/rexleimo/aios

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 skill-opt-lite

README.md
[![agentmods](https://agentmods.dev/badge/skills/rexleimo/aios/skill-opt-lite.svg)](https://agentmods.dev/skills/rexleimo/aios/skill-opt-lite)
Your own site
<a href="https://agentmods.dev/skills/rexleimo/aios/skill-opt-lite"><img src="https://agentmods.dev/badge/skills/rexleimo/aios/skill-opt-lite.svg" alt="Measured on agentmods" height="20"></a>
Per session 79 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,687 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 $0.00079 $0.01687
Opus 5 $0.00039 $0.00843
Sonnet 5 $0.00016 $0.00337
Haiku 4.5 $0.00008 $0.00169

Measured 4d ago against content hash f78fa54d923c, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

skill-opt-lite 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.

skill-sources/skill-opt-lite/SKILL.md · 159 lines

How it starts

The opening of the file, as written. The whole thing — 159 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SkillOpt-Lite: Agent-Native Skill Training

Working directory: any

Train your skill documents the way neural networks train weights — iterative rollout, reflection, and validation. No external API keys. You are both the worker and the optimizer.

When to Use

  • You have a skill that doesn't work well and want to systematically improve it
  • You want to create a new skill from scratch using data-driven iteration
  • You want to know whether a skill change actually helps or hurts

MUST NOT use for:

  • One-off skill fixes (just edit the skill directly)
  • Skills that can't be objectively evaluated (purely subjective quality)

Quick Start

  1. Prepare a task set (JSON array of tasks with verifiable outcomes)
  2. Point this skill at your draft skill document
  3. Run the training loop
  4. Get an optimized best_skill.md

Training Loop

for epoch in 1..N:
  for step in 1..steps_per_epoch:
    ① ROLLOUT   — run tasks with current skill, record pass/fail
    ② REFLECT   — analyze failures, propose edits (≤ edit_budget)
    ③ AGGREGATE — deduplicate, failure-first merge
    ④ SELECT    — pick top-L edits by impact
    ⑤ UPDATE    — apply edits to skill document
    ⑥ GATE      — re-run validation, accept only if score improves
  SLOW_UPDATE — epoch-end strategic review into protected region

Read references/training-protocol.md for the full detailed protocol before starting a training run.

Required Inputs

Input Description Format
skill_path Path to the skill document to optimize .md file
tasks Task set with verifiable outcomes JSON array (see below)
valid_tasks Validation tasks (separate from training) JSON array (optional, auto-split if not provided)

Task format:

[
  {
    "id": "task-001",
    "instruction": "The task the agent should perform",
    "expected_outcome": "What success looks like (for scoring)",
    "test_command": "optional: shell command to verify success"
  }
]

Configuration Defaults

Read the full file on GitHub · 159 lines

Files

What ships with it

3 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 · 159 lines · 79 tokens per session scan A f78fa54d923c

Subscribe to this mod's changes

skill-opt-lite is a skill published in the GitHub repository rexleimo/aios (52 stars, last pushed today), licensed MIT. It adds 79 tokens to every session and 1,687 once invoked, about $0.0004 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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