bio-alignment-msa-statistics

bio-alignment-msa-statistics is a skill for Claude Code, Codex from GPTomics/bioSkills. It costs 40 tokens per session (5,613 once invoked), scanned A, original, MIT.

A toolkit for measuring statistics from a multiple sequence alignment, where DNA, RNA, or protein sequences are arranged to compare matching positions. It calculates identity, conservation, substitutions, similarity, and related measures.

In plain words
What is it for?
Use it to assess alignment quality, measure sequence divergence, count substitutions, and study conserved regions or evolutionary patterns.
Why use it?
It turns a visual alignment into numerical evidence about which positions are shared or changing across sequences.

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/gptomics/bioskills/msa-statistics
Any agent
npx skills add GPTomics/bioSkills --skill msa-statistics
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-alignment-msa-statistics

README.md
[![agentmods](https://agentmods.dev/badge/skills/gptomics/bioskills/msa-statistics.svg)](https://agentmods.dev/skills/gptomics/bioskills/msa-statistics)
Your own site
<a href="https://agentmods.dev/skills/gptomics/bioskills/msa-statistics"><img src="https://agentmods.dev/badge/skills/gptomics/bioskills/msa-statistics.svg" alt="Measured on agentmods" height="20"></a>
Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,613 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 $0.00040 $0.05613
Opus 5 $0.00020 $0.02806
Sonnet 5 $0.00008 $0.01123
Haiku 4.5 $0.00004 $0.00561

Measured 5d ago against content hash d44f58ad40ef, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

bio-alignment-msa-statistics 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 5d ago.

The scan reads SKILL.md. This mod also ships 8 executable files (examples/capra_singh_jsd.py, examples/conservation_profile.py, examples/entropy_analysis.py, …), 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:

alignment/msa-statistics/SKILL.md · 450 lines

How it starts

The opening of the file, as written. The whole thing — 450 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Version Compatibility

Reference examples tested with: BioPython 1.83+, numpy 1.26+

Before using code patterns, verify installed versions match. If versions differ:

  • Python: pip show <package> then help(module.function) to check signatures

If code throws ImportError, AttributeError, or TypeError, introspect the installed package and adapt the example to match the actual API rather than retrying.

MSA Statistics

Calculate sequence identity, conservation scores, substitution counts, and other alignment metrics.

Required Import

Goal: Load modules for alignment I/O, substitution scoring, and statistical calculations.

Approach: Import AlignIO for reading alignments, Counter for column analysis, numpy for matrix operations, and math for entropy calculations.

from Bio import AlignIO
from Bio.Align import substitution_matrices
from collections import Counter
import numpy as np
import math

Pairwise Identity

"Calculate percent identity" -> Compute the fraction of identical aligned residues between sequence pairs.

Goal: Measure sequence similarity as percent identity for individual pairs or across all sequences in an alignment.

Approach: Count matching non-gap positions divided by total aligned positions; optionally compute a full N-by-N identity matrix.

Percent Identity Definitions

There are four common denominators, producing up to 11.5% difference on the same alignment. Combined with different alignment algorithms, variation reaches 22%. Always report which method was used.

Method Denominator Code
PID1 Aligned positions including internal gaps sum(a != '-' or b != '-' for a, b in zip(s1, s2))
PID2 Aligned residue pairs only (no gaps) sum(a != '-' and b != '-' for a, b in zip(s1, s2))
PID3 Shorter sequence length (ungapped) min(len(s1.replace('-', '')), len(s2.replace('-', '')))
PID4 Mean sequence length (ungapped) (len(s1.replace('-', '')) + len(s2.replace('-', ''))) / 2

Read the full file on GitHub · 450 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. 5d ago First seen · 450 lines · 40 tokens per session scan A d44f58ad40ef

Subscribe to this mod's changes

bio-alignment-msa-statistics is a skill published in the GitHub repository GPTomics/bioSkills (1,199 stars, last pushed 20d ago), licensed MIT. It adds 40 tokens to every session and 5,613 once invoked, about $0.0002 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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