Data Validation

Data Validation is a skill for Claude Code, Codex from niels-emmer/myace. It costs 20 tokens per session (292 once invoked), scanned A, original, MIT.

A checklist for checking dataset quality before machine-learning modeling. It examines missing values, types, ranges, train/test differences, leakage, class balance, and time ordering.

In plain words
What is it for?
Use it to create a pass/fail validation report covering data shape, missing values, unusual values, distribution drift, target leakage, imbalance, and time-series ordering.
Why use it?
It catches faulty or misleading data before it wastes training time or makes a model appear more accurate than it really is.

Skill for Claude CodeCodex

Which agent this was written for is unclear — built for aider. Also seen: mentions Codex; built for aider; mentions OpenCode.

Good fit Use it to create a pass/fail validation report covering data shape, missing values, unusual values, distribution drift, target leakage, imbalance, and time-series ordering.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/niels-emmer/myace/data-validation
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 niels-emmer/myace --skill data-validation
Clone the repo
git clone --depth 1 https://github.com/niels-emmer/myace

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 Data Validation

README.md
[![agentmods](https://agentmods.dev/badge/skills/niels-emmer/myace/data-validation.svg)](https://agentmods.dev/skills/niels-emmer/myace/data-validation)
Your own site
<a href="https://agentmods.dev/skills/niels-emmer/myace/data-validation"><img src="https://agentmods.dev/badge/skills/niels-emmer/myace/data-validation.svg" alt="Measured on agentmods" height="20"></a>
Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 292 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.
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 $0.00020 $0.00292
Opus 5 $0.00010 $0.00146
Sonnet 5 $0.00004 $0.00058
Haiku 4.5 $0.00002 $0.00029

Measured 4d ago against content hash 423f66ec2b86, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

Data Validation 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.

collections/base/data-scientist/skills/data-validation/SKILL.md · 30 lines

What it actually says

Purpose

Catch data problems before they waste training time or produce misleading models.

When to use it

Before every modeling pass, especially when working with new or updated data.

Checklist

  • Shape and type check: confirm columns, dtypes, and row counts match expectations.
  • Null distribution: count and visualize missing values per column; decide on imputation strategy.
  • Value ranges: check min/max/unique values for each feature; flag out-of-domain values.
  • Train/test distribution: compare feature distributions across splits (KS test or visualization); flag drift.
  • Target leakage scan: check for time-based leakage, ID columns, future-looking features in training data.
  • Class imbalance: quantify target distribution; plan for stratification or weighting if needed.
  • Temporal ordering: for time-series data, confirm no future data leaks into training windows.

Expected output

A data validation report with PASS/FAIL per check, attached to the experiment tracker entry.

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 · 30 lines · 20 tokens per session scan A 423f66ec2b86

Subscribe to this mod's changes

Data Validation is a skill published in the GitHub repository niels-emmer/myace (1 stars, last pushed yesterday), licensed MIT. It adds 20 tokens to every session and 292 once invoked, about $0.0001 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 2026-09-03.

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