forensic-sweep

forensic-sweep is a skill for Claude Code from danielrosehill/Claude-Data-Analyst-plugin. It costs 67 tokens per session (1,556 once invoked), scanned A, original, MIT.

A data-quality investigation that looks for signs that a dataset was cleaned or altered before you received it, such as missing values being filled in, duplicates removed, or values smoothed. It helps distinguish raw data from curated data.

In plain words
What is it for?
Use it to inspect CSV, Parquet, Excel, or DuckDB data for unusual missingness, duplicate patterns, uniform formatting, statistical irregularities, and other signs of prior processing.
Why use it?
Unexpectedly tidy data may hide processing choices that affect the conclusions you draw from it.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the claude-data-analyst plugin — 14 skills shipped together

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/danielrosehill/claude-data-analyst-plugin/forensic-sweep
Any agent
npx skills add danielrosehill/Claude-Data-Analyst-plugin --skill forensic-sweep
Clone the repo
git clone --depth 1 https://github.com/danielrosehill/Claude-Data-Analyst-plugin

Made for: Claude Code.

Or install claude-data-analyst, the plugin that ships this one along with the rest of its 14 skills.

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 forensic-sweep

README.md
[![agentmods](https://agentmods.dev/badge/skills/danielrosehill/claude-data-analyst-plugin/forensic-sweep.svg)](https://agentmods.dev/skills/danielrosehill/claude-data-analyst-plugin/forensic-sweep)
Your own site
<a href="https://agentmods.dev/skills/danielrosehill/claude-data-analyst-plugin/forensic-sweep"><img src="https://agentmods.dev/badge/skills/danielrosehill/claude-data-analyst-plugin/forensic-sweep.svg" alt="Measured on agentmods" height="20"></a>
Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,556 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 5.1 $0.00067 $0.01556
Opus 5 $0.00034 $0.00778
Sonnet 5 $0.00013 $0.00311
Haiku 4.5 $0.00007 $0.00156

Measured 6d ago against content hash cfbdba23e4fc, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

forensic-sweep 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 6d 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.

skills/forensic-sweep/SKILL.md · 106 lines

How it starts

The opening of the file, as written. The whole thing — 106 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Forensic Sweep

Real-world data is messy. Clean data is often a clue that something upstream made it that way — and that "something" shapes any conclusion downstream. This skill sweeps for those tells and reports them so the user can decide whether the cleaning is legitimate (a curated public dataset) or misleading (aggregation that hides the interesting variance).

Inputs

  • Path to a dataset (CSV / Parquet / Excel / DuckDB table).
  • Optional: known provenance (where the data came from, any processing steps the user is aware of). Helps calibrate suspicion.
  • duckdb — distinct counts, null counts, distribution quantiles, digit-frequency tests.
  • uv run --with pandas --with scipy python -c '...' — Benford's law, Shapiro/KS normality, duplicate-run detection.

What to look for

1. Impossible tidiness

  • Zero nulls everywhere in a dataset that represents a real-world process that normally has some missingness (surveys, logs, transactions). Real data almost always has some nulls. Total absence suggests imputation or a dropna upstream.
  • No duplicates at all in transactional or event data where repeats are natural.
  • All strings trimmed, lowercased, single-spaced uniformly — evidence of a normalisation pipeline.
  • Dates all in the same exact format, no parsing errors — a cleaner has been through.

2. Imputation fingerprints

  • A spike at the median, mean, or mode of a column (frequency of one value disproportionate to the rest of the distribution).
  • A spike at zero in a column where zero is a plausible imputation placeholder but not a natural value.
  • Values like -999, -1, 9999, N/A, UNKNOWN, MISSING appearing frequently — sentinel values for missingness.
  • Categorical columns with an "Other" / "Unspecified" bucket at suspiciously high share (>15%).

3. Smoothing / aggregation

  • Numeric distributions that are too normal — run Shapiro-Wilk or Kolmogorov-Smirnov vs. the fitted normal. Real-world measurements are rarely textbook-normal.
  • Low kurtosis and no outliers at all (e.g. all values within 2σ of the mean). Real data has tails.
  • Time series with implausibly smooth trajectories — check first differences; if they're tightly distributed with no spikes, suspect a moving average or spline fit.
  • Rounded numbers in clusters (e.g. everything to the nearest 5 or 10) — rounding or binning upstream.

Read the full file on GitHub · 106 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. 6d ago First seen · 106 lines · 67 tokens per session scan A cfbdba23e4fc

Subscribe to this mod's changes

forensic-sweep is a skill published in the GitHub repository danielrosehill/Claude-Data-Analyst-plugin (11 stars, last pushed 4mo ago), licensed MIT. It adds 67 tokens to every session and 1,556 once invoked, about $0.0003 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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