bio-entrez-link

bio-entrez-link is a skill for Claude Code, Codex from thesecondfox/skill. It costs 44 tokens per session (2,780 once invoked), scanned A, original, MIT.

A tool for finding links between records in NCBI's biological databases, such as connecting a gene to its protein or a sequence to related publications. It uses Biopython's Entrez interface.

In plain words
What is it for?
Use it to navigate between genes, proteins, sequences, publications, and other related NCBI records.
Why use it?
It avoids searching each NCBI database separately when related records are already cross-referenced.

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/thesecondfox/skill/bio-database-access-entrez-link
Any agent
npx skills add thesecondfox/skill --skill bio-database-access-entrez-link
Clone the repo
git clone --depth 1 https://github.com/thesecondfox/skill

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-entrez-link

README.md
[![agentmods](https://agentmods.dev/badge/skills/thesecondfox/skill/bio-database-access-entrez-link.svg)](https://agentmods.dev/skills/thesecondfox/skill/bio-database-access-entrez-link)
Your own site
<a href="https://agentmods.dev/skills/thesecondfox/skill/bio-database-access-entrez-link"><img src="https://agentmods.dev/badge/skills/thesecondfox/skill/bio-database-access-entrez-link.svg" alt="Measured on agentmods" height="20"></a>
Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,780 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 $0.00044 $0.02780
Opus 5 $0.00022 $0.01390
Sonnet 5 $0.00009 $0.00556
Haiku 4.5 $0.00004 $0.00278

Measured 5d ago against content hash 7c0144b5d24a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

bio-entrez-link 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.

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.

Common_Skills/bio-database-access-entrez-link/SKILL.md · 328 lines

How it starts

The opening of the file, as written. The whole thing — 328 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+, Entrez Direct 21.0+

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.

Navigate between NCBI databases using Biopython's Entrez module (ELink utility).

"Find related records across NCBI databases" → Use ELink to discover cross-references (e.g., gene to protein, sequence to publication).

  • Python: Entrez.elink(dbfrom=..., db=..., id=...) (BioPython)
  • CLI: elink -db protein -target gene (Entrez Direct)

Required Setup

from Bio import Entrez

Entrez.email = '[email protected]'  # Required by NCBI
Entrez.api_key = 'your_api_key'          # Optional, raises rate limit

Core Function

Entrez.elink() - Cross-Database Links

Find related records in the same or different databases.

# Find proteins linked to a gene
handle = Entrez.elink(dbfrom='gene', db='protein', id='672')
record = Entrez.read(handle)
handle.close()

# Extract linked IDs
linkset = record[0]
if linkset['LinkSetDb']:
    links = linkset['LinkSetDb'][0]['Link']
    protein_ids = [link['Id'] for link in links]
    print(f"Found {len(protein_ids)} linked proteins")

Key Parameters:

Parameter Description Example
dbfrom Source database 'gene'
db Target database 'protein'
id Source record ID(s) '672' or '672,675'
linkname Specific link type 'gene_protein_refseq'
cmd Link command 'neighbor', 'neighbor_score'

ELink Result Structure

record[0]                          # First linkset
record[0]['DbFrom']                # Source database
record[0]['IdList']                # Input IDs
record[0]['LinkSetDb']             # List of link results
record[0]['LinkSetDb'][0]['DbTo']  # Target database
record[0]['LinkSetDb'][0]['LinkName']  # Link name
record[0]['LinkSetDb'][0]['Link']  # List of linked records
record[0]['LinkSetDb'][0]['Link'][0]['Id']  # Linked ID

Read the full file on GitHub · 328 lines

Files

What ships with it

1 file 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. 5d ago First seen · 328 lines · 44 tokens per session scan A 7c0144b5d24a

Subscribe to this mod's changes

bio-entrez-link is a skill published in the GitHub repository thesecondfox/skill (3 stars, last pushed 5mo ago), licensed MIT. It adds 44 tokens to every session and 2,780 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 2026-08-31.

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