Boltz2 Nim

---
name: boltz2-nim
description: >
  Use Boltz2 NIM for biomolecular structure prediction and binding affinity. Invoke for Boltz2, protein structures, protein-ligand/DNA/RNA complexes, SMILES or CCD ligands, pIC50/IC50 affinity scoring, mmCIF output, hosted NVIDIA API calls, or local Docker deployment.
license: Apache-2.0 AND CC-BY-4.0
compatibility: "requests>=2.28"
allowed-tools: Bash, Read, Write, AskUserQuestion
---

# Boltz2 NIM

Predict biomolecular structures and optional ligand affinity. Use this
`SKILL.md` for first-pass hosted/local usage; load supplemental files only when
needed:

- `references/api.md`: exact endpoints, schemas, Docker flags, response fields.
- `references/science.md`: purpose, strengths, limitations, and handoffs.
- `references/parameters.md`: prediction, sampling, MSA, template, affinity tuning.
- `references/validation.md`: mmCIF, confidence, affinity, and chemistry checks.
- `references/examples.md`: compact hosted/local payload patterns.

## Choose Mode

Ask only when context is unclear:

> Hosted NVIDIA API or local Docker NIM?

- Hosted: `https://health.api.nvidia.com/v1/biology/mit/boltz2/predict`
- Local: `http://localhost:8000/biology/mit/boltz2/predict`

Hosted requests use `Authorization: Bearer $NGC_API_KEY`. Supported local Docker
startup uses `NGC_API_KEY` (or `NVIDIA_API_KEY` via the preflight) for
registry login, entitlement checks, and first-run model downloads; pass it
into the container with `-e NGC_API_KEY`. Local inference requests use no
auth header after readiness. Warm-cache key-free startup varies by
image/version and should not be assumed.

## Local Docker

For local setup answers, copy the preflight below before `docker login`,
`docker run`, readiness, and the no-auth local request. Do not invent a cache
default or drop the `.env` load or `NVIDIA_API_KEY` fallback.

```bash
set -a
[ -f .env ] && . ./.env
set +a

if [ -z "${NGC_API_KEY:-}" ] && [ -n "${NVIDIA_API_KEY:-}" ]; then
  export NGC_API_KEY="$NVIDIA_API_KEY"
fi
: "${NGC_API_KEY:?Set NGC_API_KEY or NVIDIA_API_KEY}"
: "${LOCAL_NIM_CACHE:?Set LOCAL_NIM_CACHE}"

echo "$NGC_API_KEY" | docker login nvcr.io --username '$oauthtoken' --password-stdin

mkdir -p "${LOCAL_NIM_CACHE}"
chmod 755 "${LOCAL_NIM_CACHE}"

docker run --rm --name boltz2 --gpus all \
  --shm-size=16G \
  -e NGC_API_KEY \
  -v "${LOCAL_NIM_CACHE}:/opt/nim/.cache" \
  -p 8000:8000 \
  nvcr.io/nim/mit/boltz2:1.6.0
```

Readiness:

```bash
until curl -sf http://localhost:8000/v1/health/ready; do sleep 5; done
```

First startup downloads about 30 GB of model weights.

## Request Pattern

```python
import os
import requests

HOSTED = True
url = (
    "https://health.api.nvidia.com/v1/biology/mit/boltz2/predict"
    if HOSTED else "http://localhost:8000/biology/mit/boltz2/predict"
)
headers = {"Content-Type": "application/json"}
if HOSTED:
    headers["Authorization"] = f"Bearer {os.getenv('NGC_API_KEY')}"

payload = {
    "polymers": [{
        "id": "A",
        "molecule_type": "protein",
        "sequence": "MTEYKLVVVGACGVGKSALTIQLIQNHFVDEYDPT",
    }],
    "recycling_steps": 3,
    "sampling_steps": 50,
    "diffusion_samples": 1,
    "step_scale": 1.638,
    "output_format": "mmcif",
}
response = requests.post(url, headers=headers, json=payload, timeout=300)
response.raise_for_status()
result = response.json()
```

Payload essentials:

- Protein polymer: `{"molecule_type": "protein", "sequence": "..."}`.
- DNA/RNA polymer: add another polymer with `molecule_type` `"dna"` or `"rna"`.
- Ligand by SMILES: `{"id": "L1", "smiles": "CC(=O)OC1=CC=CC=C1C(=O)O"}`.
- Ligand by CCD: `{"id": "L1", "ccd": "ATP"}`.
- Affinity: set `"predict_affinity": True` on exactly one ligand; report
  `affinity_pic50`, `affinity_pred_value`, and `affinity_probability_binary`.
- Precomputed A3M MSA goes under the protein polymer. The A3M record uses
  `alignment`, `format`, and `rank`; do not use a stale `data` field.

```python
protein_with_msa = {
    "id": "A",
    "molecule_type": "protein",
    "sequence": "MTEYKLVVVGAGGVGKSALTIQLIQNHFVDEYDPT",
    "msa": {"msa_search": {"a3m": {
        "alignment": ">query\nMTEYKLVVVGAGGVGKSALTIQLIQNHFVDEYDPT",
        "format": "a3m",
        "rank": 0,
    }}},
}
```

## Save And Report Output

Save every `.cif` artifact and read the confidence/affinity fields using the
snippet in [`references/examples.md`](references/examples.md) under **Save
Structures And Affinity**. Visualize in PyMOL, ChimeraX, or UCSF Chimera. For
confidence/affinity sanity checks, read `references/validation.md`.

## Limits And Troubleshooting

- Polymers/request: 12. Ligands/request: 20. Chain length: 4096 residues.
- Affinity prediction supports one ligand per request and adds runtime.
- `422`: invalid sequence, invalid CCD/SMILES, malformed MSA, or multiple
  affinity ligands.
- Local URL/auth: local path has no hosted auth header; wait on `/v1/health/ready`.
- Local startup: use `--gpus all`, `--shm-size=16G`, and the `/opt/nim/.cache` mount.