Bioinformatics tool to mask low-complexity regions in protein sequences.

Install

mkdir -p .claude/skills/segmasker && curl -L -o skill.zip "https://agentskills.codes/api/skills/download/12347" && unzip -o skill.zip -d .claude/skills/segmasker && rm skill.zip

Installs to .claude/skills/segmasker

Activation

This is the description your AI agent reads to decide when to run this skill — the better it matches your request, the more reliably it fires.

Use when identifying and masking low-complexity regions in protein sequences with the SEG algorithm before BLAST or other downstream analyses.
142 chars✓ has a “when” trigger
Intermediate

Key capabilities

  • Mask low-complexity regions in protein sequences
  • Prepare sequences for `blastp` or `rpsblast`
  • Emit interval masks for downstream tools
  • Generate masked FASTA output
  • Tune SEG algorithm aggressiveness with window, locut, and hicut parameters

How it works

The skill uses the `segmasker` tool to apply the SEG algorithm to protein sequences, identifying and masking low-complexity regions based on specified parameters.

Inputs & outputs

You give it
Protein sequences in FASTA format
You get back
Interval masks, masked FASTA, or ASN.1/XML mask metadata

When to use segmasker

  • Mask protein sequences
  • Prepare sequences for BLAST
  • Identify low-complexity regions

About this skill

segmasker

Quick Start

  • Command: segmasker
  • Local executable: /home/vimalinx/miniforge3/envs/bio/bin/segmasker
  • Version: BLAST+ 2.17.0+
  • Full reference: See references/help.md

When To Use This Tool

  • Mask low-complexity regions in protein sequences before blastp, rpsblast, or related protein-domain searches.
  • Emit interval masks, masked FASTA, or ASN.1/XML mask metadata for downstream tooling.
  • Prepare masking information from FASTA or an existing protein BLAST database.
  • Prefer dustmasker for nucleotide low-complexity masking.

Common Patterns

# 1) Produce interval-style SEG mask coordinates
segmasker \
  -in proteins.fa \
  -out proteins.seg.interval \
  -outfmt interval
# 2) Emit masked FASTA for downstream protein BLAST
segmasker \
  -in proteins.fa \
  -out proteins.masked.fa \
  -outfmt fasta
# 3) Tune SEG aggressiveness
segmasker \
  -in proteins.fa \
  -out proteins.masked.fa \
  -outfmt fasta \
  -window 12 \
  -locut 2.2 \
  -hicut 2.5

Recommended Workflow

  1. Decide whether downstream tools want coordinates, masked FASTA, or mask metadata.
  2. Run with default SEG parameters first; tune -window, -locut, and -hicut only if masking is obviously too weak or too strong.
  3. Inspect the masked output before pushing it into alignment or search workflows.
  4. Keep the unmasked protein FASTA alongside the masked output for traceability.

Guardrails

  • segmasker is the protein low-complexity masker; use dustmasker for nucleotide data.
  • The default output format is interval, not FASTA.
  • There is no separate hard-masking switch here; choose the output format that your downstream tool expects.
  • If FASTA identifiers matter downstream, consider -parse_seqids.

When not to use it

  • When masking nucleotide low-complexity data
  • When the default output format of `interval` is not desired
  • When a separate hard-masking switch is expected

Limitations

  • It is for protein low-complexity masking, not nucleotide data
  • The default output format is `interval`
  • There is no separate hard-masking switch

How it compares

This skill provides a specialized tool for protein low-complexity masking with configurable parameters and various output formats, unlike generic sequence processing tools.

Compared to similar skills

segmasker side by side with the closest alternatives in the catalog.

SkillInstallsUpdatedSafetyDifficulty
segmasker (this skill)04moReviewIntermediate
llm-evaluation62moNo flagsAdvanced
evaluating-llms-harness37moReviewAdvanced
qutip47moReviewAdvanced

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