An AXQuant (AXQ) mixed-precision MLX checkpoint for Apple Silicon, converted directly from the BF16 source model. The language path is quantized while the vision tower are preserved as BF16 sidecars when present.

Development evidence — not a certified AXQuant release. This package has conversion and artifact-integrity records, but it does not publish measured quality, long-context, kernel-speed, or MTP-speed evidence. Do not interpret the AXQ product label as a benchmark claim.

Stable-name v2. main serves the audited v2 artifact for backward compatibility. The same revision is tagged v2; the replaced artifact remains recoverable at legacy-pre-v2.

Model details

Property	Value
Base model	mistralai/Mistral-Small-3.1-24B-Instruct-2503
Source revision	`68faf511d618ef198fef186659617cfd2eb8e33a`
Product family	`mistral3`
Source architecture	`Mistral3ForConditionalGeneration` (dense); text path optimized
Main-model parameters	24.01B logical parameters
Quantizer	AXQuant `1.2.0`
Hub budget class	`4bit`
Artifact edition	`v2`
AXQuant base precision class	`4bit`
Planned storage-adjusted BPW	5.1500
Measured main-model BPW	5.1500
Measured total BPW	5.1500
Safetensors weight size	15.46 GB
Approximate complete download	15.48 GB
Configured maximum context	131,072 tokens; practical limits depend on unified memory
MLX-LM compatibility	Standard text inference, compatibility level B
AX Engine native execution	Not established; no validated native manifest is included
MTP present	`False`
Vision sidecar present	`True`

This repository contains MLX Safetensors. It does not contain PyTorch or GGUF weights.

Choosing an AXQ pack

AXQ names describe a storage-budget product class, not one uniform precision applied to every tensor. Protected tensors remain at higher precision, so the exact measured BPW is authoritative. In particular, a 6bit-named mixed plan may retain 4bit as its base precision while selecting 6-bit, 8-bit, or BF16 for other tensors to meet an approximately 6-BPW total budget. Protection floors can also raise a 4bit-named pack close to (or above) a 6bit budget on small or heavily protected models.

Sibling	Intended trade-off
4bit sibling	Lower-storage AXQ budget; check its exact BPW
6bit sibling	Higher average precision near the 6-BPW budget

See the AutomatosX MLX model catalog for related MLX and OptiQ alternatives.

Download

bash

python -m pip install -U huggingface_hub
hf download AutomatosX/AX-Mistral-Small-3.1-24B-Instruct-2503-MLX-AXQ-4bit --local-dir ./AX-Mistral-Small-3.1-24B-Instruct-2503-MLX-AXQ-4bit

Allow at least 15.48 GB of free disk space. Pin the resulting Hub commit in reproducible deployments rather than relying indefinitely on main.

Run with MLX-LM

bash

python -m pip install -U mlx-lm
mlx_lm.generate \
  --model AutomatosX/AX-Mistral-Small-3.1-24B-Instruct-2503-MLX-AXQ-4bit \
  --prompt "Explain mixed-precision quantization in three sentences." \
  --max-tokens 128 \
  --temp 0.0

MLX-LM compatibility covers standard text/backbone inference. It may ignore AXQuant runtime metadata and optional sidecars (vision.safetensors, mtp.safetensors); this command therefore does not establish MTP acceleration or vision-language quality. The artifact records MLX 0.32.0 and MLX-LM 0.31.3 from conversion.

AX Engine status

This package does not include a validated native model-manifest.json, so AX Engine execution is not established by this release. The AX Engine fields in axquant_runtime.json describe the intended compatibility contract, not observed runtime evidence. Use the MLX-LM path above for standard text/backbone inference. The artifact records AX Engine version not recorded, but version discovery alone is not a runtime check.

Quantization layout

Main-weight precision	Parameters	Share
`4bit`	22.23B	92.58%
`8bit`	671.09M	2.79%
`bf16`	1.11B	4.62%

Quantization methods: affine, bf16.
Group sizes used by quantized assignments: 32, 64.
MTP sidecar: not included.
Vision sidecar: 222 tensors, 438.96M parameters, 0.88 GB, BF16.
Optimization scope: text-path.
Support tier: convertible.

BF16 sidecars, when present, are included in total download size. Their presence does not by itself establish MTP acceleration or vision-language quality.

Evidence and validation status

Check	Status
Planning evidence	`architecture_prior`
Calibration	none; the allocation is based on architecture priors
Quantizer execution	281/281 recorded module conversions succeeded; 0 fallbacks
AX Engine native manifest	not included
Quality versus BF16 or uniform baselines	Not published; no quality-retention claim
MTP acceptance and speed	not measured; no MTP speedup claim
AX Engine kernel evidence	`unmeasured`
Vision-language quality	Not evaluated or claimed; vision tensors are preserved at BF16
Long-context quality	131,072-token capacity is config metadata, not a validated claim
Release certification	Not certified; formal AXQuant M0-M8 gates are not closed

Intended use and limitations

Intended for local development and evaluation on Apple Silicon with MLX-compatible runtimes.
No minimum unified-memory figure is claimed; loadability depends on model size, context length, KV-cache policy, runtime buffers, and other processes using unified memory.
Architecture-prior allocation is not measured sensitivity. It must not be presented as measured model quality.
Vision weights are byte-preserved at BF16, but this release does not claim validated VLM quality.
The configured context window can require substantially more memory as the KV cache grows.
AX Engine execution is not established because this package has no validated native manifest.
Upstream capabilities, limitations, biases, and responsible-use guidance still apply.

Provenance and audit files

axquant_manifest.json: package identity, byte accounting, runtime contract, software versions, and file checksums.
axquant_plan.json: per-tensor precision decisions and planning evidence.
axquant_quantizer_execution.json: conversion coverage and fallback records.
axquant_runtime.json: declared AX Engine and MLX-LM compatibility metadata; runtime checks remain separate evidence.
axquant_vision_sidecar_manifest.json: protected vision tensor provenance.

All published provenance uses repository-relative paths. Local source paths are stripped before publication. The checkpoint was converted from BF16 rather than re-quantized from an OptiQ artifact. Parallel OptiQ repositories use a different quantizer and should not be assumed to have identical BPW or quality.

License

The checkpoint follows the upstream model license where applicable (often Apache License 2.0). See the mistralai/Mistral-Small-3.1-24B-Instruct-2503 model card for license terms, model limitations, and responsible-use guidance.