Model reference · open weights

O2

LLMs ant-intl Text gen 1 build Open weights 615 dl/mo

O2 is an open-weight language model from ant-intl. O2-9b-preview (BF16) weighs 18.8 GB; the smallest configuration that runs it is RTX 4090 24 GB.

For self-hosting, compare this build's requirements below with the GPU you plan to rent.

  • O2-9B-Preview is a 9.4B parameter text-generation model developed by Ant International for agentic reasoning, tool use, and coding.
  • It is initialized from Qwen3.5-9B and trained using interactions from deployed office and software-development runtimes.
  • The model supports a context length of 262,144 tokens and is released under the Apache 2.0 license.

Summary of the ant-intl/O2-9b-preview model card, 2026-10-01

What it is

Released byant-intl
Released2026-09-02
Parameters9.4B
VRAM18.8 GB for the weights

What it runs on

Memory and cards for O2-9b-preview (BF16)

18.8 GBweights, file size
33 MBcache per 1K tokens
103 MBfixed state per request
2.1 GBruntime overhead, at least
262,144 tokenscontext max
CardRequests at onceContext maxMemory
8K each32K each
RTX 3060 12 GB … RTX 4060 Ti 16 GB
2 smaller cards
RTX 3090 24 GB6269K23.4 GB
RTX 4090 24 GB6268K23.4 GB
RTX 5090 32 GB278all 256K31.0 GB
L40S 48 GB6119all 256K44.0 GB
A100 80 GB15448all 256K78.2 GB
H100 80 GB13943all 256K78.1 GB
RTX PRO 6000 Blackwell 96 GB18157all 256K93.8 GB
DGX Spark (GB10) 128 GB unified21768all 256K107 GB
H200 141 GB30094all 256K138 GB
B200 180 GB401126all 256K176 GB
2× RTX 4060 Ti 16 GB
tensor parallel
206227K15.4 GB a card
2× RTX 4090 24 GB
tensor parallel
6320all 256K23.4 GB a card
2× RTX 3090 24 GB
tensor parallel
6320all 256K23.4 GB a card
Memory needed at each load
Requests at once8K tokens each32K tokens each
121.3 GB22.1 GB
522.8 GB26.8 GB
823.9 GB30.4 GB
1626.9 GB39.8 GB
3232.8 GB58.6 GB
6444.7 GB96.3 GB

One card, with vLLM's small-card settings.

From the model card

What ant-intl says about O2

Read the model card

A 9B agentic model trained from interactions generated inside runtimes deployed across real office and software-development workflows.

Preliminary Evaluation

O2-9B-Preview was evaluated across eleven reasoning, tool-use, and coding benchmarks. We report its same-size Qwen3.5-9B base alongside larger O2 checkpoints and cross-scale reference models. Scores are shown on their original scales, and higher is better. The average is the unweighted mean of the eleven displayed benchmarks.

O2-9B-Preview improves ten of the eleven reported point estimates over the base model. In a separate comparison of complete post-training pipelines built on the same 9B base, it achieves the highest reported aggregate score: 64.07, compared with 61.08 for PowerOPD, 60.22 for GRPO, 57.05 for SFT, and 54.59 for CurryOPD.

These results are preliminary. They come from an author-provided evaluation report without repeated seeds, uncertainty intervals, or matched training and runtime-compute budgets. They characterize the released checkpoint but do not isolate the causal contribution of any individual training component.

Overview

O2-9B-Preview is a 9B-parameter preview model developed by Ant International and initialized from Qwen3.5-9B. It is designed for agentic reasoning, tool use, and coding.

The defining feature of O2-9B-Preview is where its post-training experience comes from. Instead of relying only on static prompt-response datasets, we deployed an executable agent runtime in real operational environments—including international merchant customer-service workflows and the daily development workflows of dozens of engineers—and trained the model from the resulting interactions.

Within these runtimes, the model acts on a task, observes the consequence, receives an executable verification result, and, when necessary, repairs its action. These student-visited states are preserved as structured training records and distilled back into the model. O2-9B-Preview is therefore trained not only on what a successful answer looks like, but also on what happened when an action was executed, why it failed, and how it was repaired.

What Makes O2 Different

Trained where agents actually work

The training loop is connected to deployed office and development environments rather than an isolated text-only data pipeline. It captures interactions with tools, repositories, tests, workflow state, and domain rules under the same kinds of conditions in which agents are expected to operate.

Learning from executable outcomes

For each task, the runtime constructs a task-conditioned verifier suite that checks observable evidence such as tool results, environment state, code execution, repository tests, schema constraints, and domain rules. A verifier pass is treated as a certificate under a specific, versioned suite—not as unrestricted ground truth.

Preserving failures and repairs

The runtime records the task context, model action, executed consequence, verifier outcome, localized failure feedback, and repaired action when one exists. Accepted, rejected, repaired, and unresolved attempts remain available for learning instead of discarding everything except the final answer.

Runtime on-policy distillation

O2-9B-Preview is post-trained with Runtime OPSD, an on-policy sequence-distillation recipe over states visited by the student in the deployed runtime. Oracle outcomes anchor complete trajectories, while teacher and student score tokens under the same task context, runtime state, and generated prefix. This keeps the learning signal aligned with the information available to the model at inference time.

Training Loop

  1. A task and its runtime profile are compiled into a versioned verifier suite.
  2. The model acts in the executable task environment.
  3. The runtime checks the resulting state and returns an auditable outcome.
  4. Failed obligations produce localized, failure-only feedback for bounded repair.
  5. The interaction is stored as a versioned training record, including failures and repair transitions.
  6. Runtime OPSD distills these student-visited records into the next model checkpoint.

This process turns deployed task environments into a renewable source of grounded training experience.

Model Details

FieldDescription
ModelO2-9B-Preview
DeveloperAnt International
Parameters9B
Base modelQwen3.5-9B
Training paradigmVerifier-guided runtime data synthesis and Runtime OPSD
Primary capability groupsReasoning, tool use, and coding
Release stagePreview

Intended Use

O2-9B-Preview is intended for research and evaluation involving:

  • agentic reasoning over multi-step tasks;
  • tool-using assistants operating in controlled environments;
  • software-development and repository workflows;
  • office and business-process automation with explicit validation; and
  • research on runtime learning, executable verification, and on-policy distillation.

For state-changing or business-critical actions, the model should be deployed with sandboxed tools, least-privilege access, independent checks, and human review.

Limitations

  • Preview evidence. The current results are single-report point estimates without multi-seed uncertainty or matched-compute controls.
  • Capability-specific regression. Despite a higher aggregate score, O2-9B-Preview scores lower than its base model on BFCL V4 in the reported evaluation.
  • Partial verification. Executable verifiers encode partial specifications. They can miss valid behavior, accept incorrect behavior, or reward shortcuts when checks are incomplete.
  • Runtime dependence. Performance can depend on tool availability, verifier coverage, environment state, and the compatibility of the deployment runtime with the training setup.
  • Operational claims. Deployment of the training runtime in merchant-service and engineering workflows establishes real-world operational scope, not a contro

Quoted from the model card on Hugging Face. The full card is behind the Hugging Face link above.

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