ptq

A guide for reducing the size and calculation cost of a trained machine-learning model after training. It uses ModelOpt to create a smaller checkpoint that can be loaded from Hugging Face.

In plain words
What is it for?
Use it to quantize language, mixture-of-experts, and vision-language models with formats such as NVFP4, FP8, INT8, or INT4 AWQ. It covers preparing the environment, checking model support, and running the quantization process.
Why use it?
It helps when a pretrained model needs to run with lower memory or faster calculations. The guide also helps determine whether the model is supported and whether extra code or a custom script is needed.

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/nvidia/model-optimizer/ptq
Any agent
npx skills add NVIDIA/Model-Optimizer --skill ptq
Clone the repo
git clone --depth 1 https://github.com/NVIDIA/Model-Optimizer

Made for: Claude Code, Codex.

Per session 106 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,893 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 $0.00106 $0.02893
Opus 5 $0.00053 $0.01447
Sonnet 5 $0.00021 $0.00579
Haiku 4.5 $0.00011 $0.00289

Measured 2d ago against content hash 2cddd9d95def, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

ptq 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 2d 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.

plugins/modelopt/skills/ptq/SKILL.md · 215 lines

How it starts

The opening of the file, as written. The whole thing — 215 lines — stays where its author put it; the contents beside it link to each section on GitHub.

ModelOpt Post-Training Quantization

Produce a quantized checkpoint from a pretrained model. Read examples/hf_ptq/README.md first — it has the support matrix, CLI flags, and accuracy guidance.

Use quant-recipe-search for multi-candidate recipe exploration or optimization. Use this skill for each selected recipe's PTQ run.

Step 1 — Environment

Use the common skill's environment-setup.md and workspace-management.md. After completing them you should know:

  • ModelOpt source is available
  • Local or remote (+ cluster config if remote)
  • SLURM / Docker+GPU / bare GPU
  • Launcher available?
  • Which workspace to use

Step 2 — Is the model supported?

Check the support table in examples/hf_ptq/README.md for verified HF models.

  • Listed → supported, use hf_ptq.py (step 4A/4B)
  • Not listed → read references/unsupported-models.md to determine if hf_ptq.py can still work or if a custom script is needed (step 4C)

Step 2.5 — Check for model-specific dependencies

If the model uses trust_remote_code (check config.json for auto_map), inspect its custom Python files for imports not present in the container:

grep -h "^from \|^import " <model_path>/modeling_*.py | sort -u

Known dependency patterns:

Import found Packages to install
from mamba_ssm / from causal_conv1d mamba-ssm causal-conv1d (Mamba/hybrid models: NemotronH, Jamba)

If extra deps are needed:

  • Launcher (4B): set EXTRA_PIP_DEPS in the task's environment section — ptq.sh installs them automatically
  • Manual (4A): unset PIP_CONSTRAINT && pip install <deps> before running hf_ptq.py

Step 3 — Choose quantization format

First, check for a model-specific recipe:

ls modelopt_recipes/models/ 2>/dev/null
ls modelopt_recipes/huggingface/<model_type>/ptq/ 2>/dev/null  # per-arch; <model_type> from local config.json (Hub ID: AutoConfig.from_pretrained)

If a model-specific recipe exists, prefer --recipe <path> — but inspect its include/exclude patterns rather than assuming (e.g. for VLMs, confirm the vision tower is actually excluded).

Read the full file on GitHub · 215 lines

Files

What ships with it

5 files 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. 2d ago First seen · 215 lines · 106 tokens per session scan A 2cddd9d95def

Subscribe to this mod's changes

ptq is a skill published in the GitHub repository NVIDIA/Model-Optimizer (3,612 stars, last pushed 2d ago), licensed Apache-2.0. It adds 106 tokens to every session and 2,893 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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