chai1

chai1 is a skill for Claude Code, Codex from aipoch/open-science. It costs 98 tokens per session (1,287 once invoked), scanned A, original, Apache-2.0.

A structure-prediction tool for complexes containing proteins, DNA, RNA, and small molecules. It uses the Chai-1 model and accepts molecular sequences plus ligand descriptions such as SMILES, a text format for chemical structures.

In plain words
What is it for?
Predicting antibody–antigen, protein–protein, protein–RNA, protein–DNA, and protein–ligand structures. It can also be used to re-check designed binding proteins.
Why use it?
It helps estimate how several biological molecules or a drug-like molecule may arrange themselves before testing them in the lab. Its scores help rank the predicted structures.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Predicting antibody–antigen, protein–protein, protein–RNA, protein–DNA, and protein–ligand structures. It can also be used to re-check designed binding proteins.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/aipoch/open-science/chai1
About the project

Open Science is a local-first, model-agnostic workbench for reproducible scientific research. Scientists use its AI agents, Python and R execution, data connectors, and traceable outputs for tasks such as literature review, analysis, simulation, and visualization across macOS, Windows, and Linux.

aipoch/open-science · 3,964 stars · on GitHub · aipoch.com

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 aipoch/open-science --skill chai1
Clone the repo
git clone --depth 1 https://github.com/aipoch/open-science

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 chai1

README.md
[![agentmods](https://agentmods.dev/badge/skills/aipoch/open-science/chai1.svg)](https://agentmods.dev/skills/aipoch/open-science/chai1)
Your own site
<a href="https://agentmods.dev/skills/aipoch/open-science/chai1"><img src="https://agentmods.dev/badge/skills/aipoch/open-science/chai1.svg" alt="Measured on agentmods" height="20"></a>
Per session 98 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,287 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 $0.00098 $0.01287
Opus 5 $0.00049 $0.00643
Sonnet 5 $0.00020 $0.00257
Haiku 4.5 $0.00010 $0.00129

Measured 7d ago against content hash d51de643f87e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

chai1 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 7d 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

  • chai1 — 100% identical, 8 lines differ
resources/skills/chai1/SKILL.md · 112 lines

How it starts

The opening of the file, as written. The whole thing — 112 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Chai-1

Chai-1 is an all-atom diffusion co-folder in the same family as Boltz-2 and AlphaFold3: a multi-entity FASTA in, mmCIF plus pTM/ipTM/pLDDT out, with protein, RNA, DNA, and SMILES-ligand chains all first-class. It and boltz cover the same surface; running both and keeping designs that pass either is a common consensus filter, and Chai's Python entry point makes it the easier of the two to embed in a loop. Code and weights are Apache-2.0 — commercial use including drug discovery is explicitly permitted (github.com/chaidiscovery/chai-lab).

Running it

from pathlib import Path
from chai_lab.chai1 import run_inference

Path("complex.fasta").write_text("""
>protein|name=target
MVTPEGNVSLVDESLLVGVTDEDRAVRS...
>protein|name=binder
AIQRTPKIQVYSRHPAENG...
>ligand|name=cofactor
CCCCCCCCCCCCCC(=O)O
""".strip())

candidates = run_inference(
    fasta_file=Path("complex.fasta"),
    output_dir=Path("out/"),
    num_trunk_recycles=3,
    num_diffn_timesteps=200,
    seed=42,
    device="cuda:0",
    use_esm_embeddings=True,
)
print([rd.aggregate_score.item() for rd in candidates.ranking_data])

The FASTA header is >{entity_type}|name={id} with entity_type ∈ {protein, rna, dna, ligand}; ligand records carry a SMILES string as the sequence body, and modified residues are written inline as ...AAK(SEP)AAG.... From the shell the same job is chai-lab fold complex.fasta out/ --use-msa-server. Without --use-msa-server (or use_msa_server=True in Python) the model runs on ESM embeddings alone, which is faster but typically a few ipTM points behind the MSA-backed run.

output_dir receives pred.model_idx_{0..4}.cif plus a matching scores.model_idx_{N}.npz per sample with aggregate_score, ptm, iptm, per_chain_ptm, and clash flags. Rank by aggregate_score; treat iptm > 0.5 as a soft pass for an interface. The function refuses a non-empty output_dir, so clear or rotate it between calls.

Unset CHAI_DOWNLOADS_DIR fails mid-run with PermissionError on a read-only image

Read the full file on GitHub · 112 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. 7d ago First seen · 112 lines · 98 tokens per session scan A d51de643f87e

Subscribe to this mod's changes

chai1 is a skill published in the GitHub repository aipoch/open-science (3,964 stars, last pushed today), licensed Apache-2.0. It adds 98 tokens to every session and 1,287 once invoked, about $0.0005 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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