arnesto: Skill for Claude Code

.agents/skills/ml-best-practices/SKILL.md

ml-best-practices is a skill for Claude Code, Codex from saski/arnesto. It costs 129 tokens per session (2,023 once invoked), scanned A, a copy of ml-best-practices, Unlicense.

A set of rules for handling machine-learning work and data analysis, including how to structure notebooks and interpret results.

In plain words
What is it for?
Use it for clustering, classification, regression, forecasting, statistical testing, model comparison, and data-analysis notebooks.
Why use it?
It helps keep analysis understandable and reduces common mistakes in data preparation, model comparison, and reporting.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

This is saski/arnesto's own configuration. It tells Claude Code and Codex how to work on arnesto itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything arnesto configures →

Reuse

Borrowing it

Nothing to install: this file belongs to saski/arnesto. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/saski/arnesto/main/.agents/skills/ml-best-practices/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/saski/arnesto

Made for: Claude Code, Codex.

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README.md
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Per session 129 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,023 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod 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 $0.02023
Opus 5 $0.00064 $0.01012
Sonnet 5 $0.00026 $0.00405
Haiku 4.5 $0.00013 $0.00202

Measured 3d ago against content hash ae010fd52e6b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

ml-best-practices 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 3d 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.

Origin

This is a copy

100% identical to ml-best-practices — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/ml-best-practices/SKILL.md · 213 lines

How it starts

The opening of the file, as written. The whole thing — 213 lines — stays where its author put it; the contents beside it link to each section on GitHub.

ML Best Practices

I want to read a story about the data, not just run code. Ensure every code cell is followed by a markdown cell analyzing the results. End the notebook with a summary comprehensively answering the prompt.

If there is a good match between the user's request and a corresponding example plan, then adapt the example plan to fully answer the user's request:

Clustering:

Identify distinct groups based on their features.

  • Understand the schema and field descriptions.
  • Visualize features referenced in the prompt (e.g., with histograms, scatterplots).
  • Transform dates into timestamps.
  • Before applying encoders, check if the dataset already contains pre-encoded features and prefer existing numerical representations.
  • Prefer to keep data instead of dropping it when possible.
  • Transform ordinal data with an ordinal encoder.
  • Transform nominal data with a one hot encoder.
  • Standardize numerical features.
  • Perform clustering with a range of values, and collect the silhouette score.
  • Choose the optimal number of clusters based on the silhouette score.
  • Use dimensionality reduction (e.g., PCA) to project the data into two dimensions.
  • Scatterplot the samples in two dimensions with cluster labels as the hue.
  • Scatterplot the samples in two dimensions with a discrete feature as the hue.
  • Describe the clusters in text by feature distributions or typical feature values.
  • Conclusion: comprehensively answer the prompt in a final markdown cell.

Time Series Forecasting:

Develop a predictive model to estimate future values based on historical trends. How might different modeling approaches impact the prediction accuracy?

  • Understand the schema and field descriptions.
  • Visualize the target feature over time at a reasonable granularity.
  • Always perform a chronological split on the data to create training, validation, and test sets.
  • Are there seasonal trends?
  • Test for stationarity.
  • Discuss possible modeling approaches. How might different modeling approaches impact the prediction accuracy?
  • Train two time series forecasting models to predict the target feature. Use previous seasonality and stationarity information as model hyperparameters.
  • Predict the target feature for the training and validation sets.
  • Optionally, hypertune models with the validation set.
  • Visualize the actual and predicted target feature vs time for each model on the training and validation sets.
  • Evaluate the validation performance with error metrics.
  • Select a model.
  • Retrain the selected model on the test and validation sets.
  • Predict the test values with the selected model.
  • Visualize the average target feature and the predicted test values.
  • Conclusion: comprehensively answer the prompt in a final markdown cell.

Read the full file on GitHub · 213 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. 3d ago First seen · 213 lines · 129 tokens per session scan A ae010fd52e6b

Subscribe to this mod's changes

ml-best-practices is a skill published in the GitHub repository saski/arnesto (5 stars, last pushed today), licensed Unlicense. It adds 129 tokens to every session and 2,023 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to ml-best-practices, differing in 0 lines, and is treated as a copy.