bio-chipseq-peak-calling

bio-chipseq-peak-calling is a skill for Claude Code, Codex from GPTomics/bioSkills. It costs 138 tokens per session (5,558 once invoked), scanned A, original, MIT.

A guide for finding peaks in ChIP-seq data, where a peak is a genomic region with unusually strong protein–DNA binding signal. It compares the experimental sample with an input control or background.

In plain words
What is it for?
Use it to call transcription-factor or histone-mark peaks with MACS, HOMER, or SPP, and assess replicate consistency with IDR.
Why use it?
It turns aligned sequencing reads into candidate binding regions and helps account for whether the target produces narrow or broad signals.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: positional $N argument.

Good fit Use it to call transcription-factor or histone-mark peaks with MACS, HOMER, or SPP, and assess replicate consistency with IDR.

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Install with agentmods
npx agentmods add skills/gptomics/bioskills/peak-calling
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 GPTomics/bioSkills --skill peak-calling
Clone the repo
git clone --depth 1 https://github.com/GPTomics/bioSkills

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 bio-chipseq-peak-calling

README.md
[![agentmods](https://agentmods.dev/badge/skills/gptomics/bioskills/peak-calling/github.svg)](https://agentmods.dev/skills/gptomics/bioskills/peak-calling)
Your own site
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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 bio-chipseq-peak-calling

Your own site · 80×15
<a href="https://agentmods.dev/skills/gptomics/bioskills/peak-calling"><img src="https://agentmods.dev/badge/skills/gptomics/bioskills/peak-calling.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 138 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,558 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 $0.00138 $0.05558
Opus 5 $0.00069 $0.02779
Sonnet 5 $0.00028 $0.01112
Haiku 4.5 $0.00014 $0.00556

Measured 6d ago against content hash 9662768f54fc, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

bio-chipseq-peak-calling 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.

The scan reads SKILL.md. This mod also ships 1 executable file (examples/macs3_peak_calling.sh), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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

Copies of this mod

1 near-identical copy found in the catalogue:

chip-seq/peak-calling/SKILL.md · 279 lines

How it starts

The opening of the file, as written. The whole thing — 279 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Version Compatibility

Reference examples tested with: MACS3 3.0.4+, MACS2 2.2.9+, HOMER 4.11+, SPP 1.16+, samtools 1.19+, bedtools 2.31+, IDR 2.0.4+.

Before running, verify versions: <tool> --version and <tool> --help to confirm flags. If a flag is missing, check the changelog — MACS2->MACS3 is API-compatible for callpeak but predictd, bdgpeakcall, and hmmratac differ.

ChIP-seq Peak Calling

"Identify protein-DNA binding sites from ChIP-seq alignments" -> Detect statistically enriched genomic regions by comparing IP signal to input control (or genomic background), with peak shape (narrow/broad) determined by target biology (TF vs histone mark).

  • CLI (ENCODE TF default): macs2 callpeak -t chip.bam -c input.bam -f BAM -g hs -n sample --keep-dup all -p 1e-2
  • CLI (ENCODE histone default): same with --broad --broad-cutoff 0.1 for H3K27me3, H3K9me3, H3K36me3
  • CLI (alternative): macs3 callpeak ... (API-identical, active development), HOMER findPeaks tags/ -style histone -i input_tags/, SPP via phantompeakqualtools wrapper

ENCODE TF pipeline still uses SPP for peak ranking + IDR, with MACS2 producing the signal tracks. Histone pipeline uses MACS2 + naive overlap (IDR is too conservative for histone signal dynamic range). MACS3 is the actively maintained successor; MACS2 receives only bug fixes.

Critical Pre-Call Validation

Before any peak calling, three things must be true or the output is unreliable:

  1. Antibody validated — KO/KD orthogonal control, peptide-array specificity for histone modifications, or vendor-provided CRISPR-validated lot (Epicypher, CST). "ChIP-grade" marketing is not validation. See chipseq-qc.
  2. Fragment-size distribution is sane — TF ChIP should show sub-nucleosomal (~50-100 bp) enrichment; histone ChIP should show clean mono- (~150) and di-nucleosomal (~300) peaks. Flat distribution = over-sonication; rescue is impossible. Check via samtools view -f 0x2 sample.bam | awk '{print $9}' | sort | uniq -c.
  3. Input control matches — Sonicated input is biased toward open chromatin; MNase input toward nucleosomes. Input from a different library prep batch or fragmentation method introduces bias that subtraction cannot fix.

Read the full file on GitHub · 279 lines

Files

What ships with it

2 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. 6d ago First seen · 279 lines · 138 tokens per session scan A 9662768f54fc

Subscribe to this mod's changes

bio-chipseq-peak-calling is a skill published in the GitHub repository GPTomics/bioSkills (1,199 stars, last pushed 25d ago), licensed MIT. It adds 138 tokens to every session and 5,558 once invoked, about $0.0007 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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