Agent skill

Chai1

by JimLiu in JimLiu/science-skills

Structure prediction for protein, nucleic-acid, and small-molecule complexes with the Chai-1 foundation model (Chai Discovery 2024, github.com/chaidiscovery/chai-lab).

Apache-2.0Auto-check passedResearch & Science

Install Chai1

skills CLI
$ npx skills add JimLiu/science-skills --skill chai1 -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install JimLiu/science-skills chai1 --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/JimLiu/science-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/chai1 .claude/skills/chai1 && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
chai1
GitHub stars
227
Used in
4 other repos
Token cost
~1.2k tokens
SKILL.md length
407 words
Files
1
Skills in repo
27
Repo updated
First seen
Licence
Apache-2.0

At a glance

Structure prediction for protein, nucleic-acid, and small-molecule complexes with the Chai-1 foundation model (Chai Discovery 2024, github.com/chaidiscovery/chai-lab).

  • Tasks that involve Protein structure and design
  • SKILL.md covers Running it, Unset CHAI_DOWNLOADS_DIR fails…, No-MSA mode still loads a 3… and Errors worth recognizing
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
  • Tasks that involve Drug discovery and cheminformatics

What it does

Chai1 is an agent skill from JimLiu/science-skills. Structure prediction for protein, nucleic-acid, and small-molecule complexes with the Chai-1 foundation model (Chai Discovery 2024, github.com/chaidiscovery/chai-lab). Reach for this skill to predict an antibody-antigen or protein-ligand complex from a single FASTA, to re-fold designed binders as an AlphaFold-multimer alternative, or to drive co-folding from Python for batched campaigns on a GPU.

Its SKILL.md is about 1.2k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Research & Science, covering Protein structure and design and Drug discovery and cheminformatics. It works with Python, GitHub and AlphaFold. The licence is Apache-2.0.

When your agent uses it

  • Tasks that involve Protein structure and design
  • Tasks that involve Drug discovery and cheminformatics

Example prompts

  • “/chai1”

Requirements

  • Python 3

What it can do on your machine

Read from SKILL.md and the folder at commit fb309c3. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md (its code samples are python).

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Chai1 loads about 1.2k tokens when it runs. Until then it costs about 101 tokens; SKILL.md has 407 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~101
When it runs · the whole SKILL.md, loaded when a task matches
~1.2k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from JimLiu/science-skills at commit fb309c3, republished under its Apache-2.0 licence (© JimLiu). 407 words, ~1,151 tokens.

Download SKILL.mdSave it as .claude/skills/chai1/SKILL.md (or your agent's skills folder).
name
chai1
description
Structure prediction for protein, nucleic-acid, and small-molecule complexes with the Chai-1 foundation model (Chai Discovery 2024, github.com/chaidiscovery/chai-lab). Reach for this skill to predict an antibody-antigen or protein-ligand complex from a single FASTA, to re-fold designed binders as an AlphaFold-multimer alternative, or to drive co-folding from Python for batched campaigns on a GPU.
license
Apache-2.0
category
biomodels
requirements
gpu
metadata.display-name
Chai-1

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

python
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

Chai downloads ~5 GB on the first inference call (not at install time), including its own traced ESM2-3B for the embedding path. If CHAI_DOWNLOADS_DIR is unset, the default is inside site-packages: on a read-only image that fails with a confusing PermissionError mid-run, and on a writable one it silently re-downloads ~5 GB into the container on every cold start. Export the variable to a persisted volume so the download happens once.

Show full SKILL.md (131 more words)Show less

No-MSA mode still loads a 3 B-parameter ESM — same VRAM, not less

use_esm_embeddings=True without an MSA still loads a 3-billion-parameter language model into GPU memory alongside the trunk; it removes the MSA-server round-trip, not the VRAM cost. If you OOM, drop num_diffn_timesteps or fold fewer chains per call rather than expecting the no-MSA mode to fit a smaller card.

Errors worth recognizing

You seeIt means / do this
PermissionError under site-packages/chai_lab/...CHAI_DOWNLOADS_DIR not set on a read-only image — export it to a writable path or the pre-populated mount.
RuntimeError: CUDA out of memory during ESM embeddingThe traced ESM2-3B is loading alongside the trunk — use an 80 GB tier or split chains across calls.

Next: filter survivors on confidence/clash metrics or feed them back to proteinmpnn for the next design round.

© JimLiu, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/chai1 of JimLiu/science-skills.

Open the folder on GitHubat commit fb309c3

Used in 4 other repositories

We found 4 copies of this SKILL.md (exact, near-identical or edited) in other folders, from 4 other GitHub owners. This page covers the copy in JimLiu/science-skills, which our catalogue first saw on October 7, 2026.

Compare with similar skills

Chai1 next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Chai1 compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Chai1 this skillJimLiu/science-skills2274 repos~1.2kAutomated safety check: PassApache-2.0
DiffDock Molecular DockingK-Dense-AI/scientific-agent-skills48k1 repos~3kAutomated safety check: NotesMIT
Biopipelineslocbp-uzh/biopipelines109—~2.4kAutomated safety check: PassMIT
Ggetdavila7/claude-code-templates32k10 repos~6.3kAutomated safety check: PassMIT
Alphafold3VectorSpaceLab/AREX-Skill330—~1.2kAutomated safety check: PassApache-2.0
Ggetaipoch/medical-research-skills2k—~816Automated safety check: PassMIT

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  • Fair Esm2

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  • Openfold3

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Questions about Chai1

What does Chai1 do?

Structure prediction for protein, nucleic-acid, and small-molecule complexes with the Chai-1 foundation model (Chai Discovery 2024, github.com/chaidiscovery/chai-lab). Chai1 is an agent skill from JimLiu/science-skills.com/chaidiscovery/chai-lab).

When should I use Chai1?

Chai1 fits situations like: tasks that involve Protein structure and design; tasks that involve Drug discovery and cheminformatics.

How do I install Chai1 in Claude Code?

Run `npx skills add JimLiu/science-skills --skill chai1 -a claude-code`. Or copy the skill folder (skills/chai1 in JimLiu/science-skills) into .claude/skills/chai1 in your project. Claude Code loads it when a task matches its description.

How do I install Chai1 in Codex?

Run `npx skills add JimLiu/science-skills --skill chai1 -a codex`. Or copy the skill folder (skills/chai1 in JimLiu/science-skills) into .agents/skills/chai1 in your project. Codex loads it when a task matches its description.

Can I use Chai1 in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add JimLiu/science-skills --skill chai1 -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/chai1, .gemini/skills/chai1, .github/skills/chai1 and .opencode/skills/chai1 in your project.

What does Chai1 need to run?

SKILL.md names no scripts, command-line tools or credentials: Chai1 is instructions for the agent only. Our summary lists: Python 3.

Does Chai1 access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Chai1 safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Chai1 use?

Chai1 is published under the Apache-2.0 licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Chai1 use?

About 1.2k tokens (SKILL.md is roughly 4.6k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Chai1?

Skills that share tags, products or a category with Chai1: DiffDock Molecular Docking (K-Dense-AI/scientific-agent-skills, 48k stars), Biopipelines (locbp-uzh/biopipelines, 109 stars), Gget (davila7/claude-code-templates, 32k stars) and Alphafold3 (VectorSpaceLab/AREX-Skill, 330 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Chai1?

JimLiu (a GitHub user) maintains it in JimLiu/science-skills, which has 227 GitHub stars. The repository holds 27 skills in this directory. The repository was last updated on July 1, 2026.

Source: JimLiu/science-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.