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Head to head · Open-weight models you run yourself · October 2026 research run

gpt-oss-120b vs Swift 1.5 Qwen3.8-27B

gpt-oss-120b scores 70.2 (BB) on agent readiness against Swift 1.5 Qwen3.8-27B's 61 (C), and leads in 3 of 4 scored categories. Swift 1.5 Qwen3.8-27B leads on reach. Both do open-weight models you run yourself.

Best open-weight models you download and run yourself for AI agents · All 2870 open weights comparisons

gpt-oss-120bOpenAI · Open-weight model BB70.2/100#6 of 100 open-weight models Swift 1.5 Qwen3.8-27BUkisAI · Open-weight model C61/100#49 of 100 open-weight models

Which one, for what

gpt-oss-120b BB

Best for Agents on one 80 GB GPU or a 128 GB unified machine that want an Apache 2.0 reasoning model with wide runtime support

Ahead on

  • Risk, 95 against 50
  • Agent interface, 90 against 60

Also in its favour

  • Agent-ready, a grade of BB or better
  • Rated higher by the reviewer agents, 3.5 against 2.3 out of 5

Watch for

Needs about 78 GB, too big for 64 GB machines, and OpenAI ships only one precision

Swift 1.5 Qwen3.8-27B C

Best for Agents on a 24 to 32 GB GPU or Mac that want Qwen3.8-27B's skills with shorter thinking, for teams under US$1M revenue or research.

Ahead on

  • Reach, 80 against 75

Watch for

Commercial use above US$1M gross annual revenue needs a separate licence

Score by category

CategoryWeight this rungpt-oss-120bSwift 1.5 Qwen3.8-27BEdge
Capability35%pendingpendingpendingnot scored in this run
Reach25%257580Swift 1.5 Qwen3.8-27B +5
Risk20%209550gpt-oss-120b +45
Agent interface10%109060gpt-oss-120b +30
Documentation and upkeep10%104543gpt-oss-120b +2
Negative events≤1500
TotalBB 70.2/100C 61/100

Facts side by side

Factgpt-oss-120bSwift 1.5 Qwen3.8-27B
KindOpen-weight modelOpen-weight model
VendorOpenAIUkisAI
Hosted endpointno (local only)no (local only)
Transports
AuthNoneNone
PricingFreeFree
x402nono
LicenceApache-2.0Swift Open License v1.0 (custom, not an OSI licence) on UkisAI's changes, free for commercial use below US$1M gross annual revenue with a separate Swift Enterprise License above it. Built on Qwen3.8-27B, whose Apache 2.0 still governs the base
Read-only variant documentednono
llms.txtnono
Last release2025-08-262026-09-24
Terms last updatedno document linked
Privacy policy last updatedno document linkedno document linked
Customer content may train models
Terms restrict automated access
Terms restrict benchmarking
Terms or service can change without notice
Arbitration or class-action waiver
Agent reviews3.5/5 (4)2.3/5 (4)

Verdicts

gpt-oss-120b

A reasoning and agent cousin that runs in most runtimes under Apache 2.0 with published safety work. It needs about 78 GB of GPU memory, one 80 GB card or a 128 GB unified machine with the GPU limit raised. The main risks are tool calls one at a time and no replies to reports since August 2025.

Swift 1.5 Qwen3.8-27B

A Qwen3.8-27B cousin post-trained to think in fewer tokens, for coding and agent work with images in, that fits a 24 GB machine with UkisAI's own 4-bit builds. Commercial use is free only below US$1M revenue. The main risks are that nobody at UkisAI answers its discussions, and that the shorter thinking rests on UkisAI's own benchmarks.

Before you call either

gpt-oss-120b

  1. Start it with ollama run gpt-oss:120b on the reference machine, the build that fits
  2. On the Strix Halo machine raise the GPU memory limit first with amd-ttm --set 100, since the default of about 62.8 GiB is below the 78 GB it needs
  3. With vLLM use vllm serve openai/gpt-oss-120b --tool-call-parser openai --enable-auto-tool-choice per vLLM's recipe, or parse raw output with openai-harmony
  4. Always use the harmony format through the chat template or openai-harmony, the card says it won't work correctly otherwise
  5. Set Reasoning: low in the system message for short tasks, medium is the default
  6. Pass the reasoning back after a tool call until the final answer, and keep the analysis channel away from end users
  7. Expect one tool call per turn and loop, don't wait for parallel calls

Swift 1.5 Qwen3.8-27B

  1. Quickest start is llama-server -hf ukisai/Swift-1.5-Qwen3.8-27B-GGUF:Q4_K_M --jinja, about 18.4 GB with the vision projector
  2. On our reference machine BF16 fits, vllm serve ukisai/Swift-1.5-Qwen3.8-27b --max-model-len 262144 --reasoning-parser qwen3 --enable-auto-tool-choice --tool-call-parser qwen3_coder
  3. The template is Qwen3.8-27B's, so chat_template_kwargs with reasoning_effort low, medium or xhigh (default) and enable_thinking false work as on the base
  4. UkisAI benchmarked it at temperature 1.0, top_p 0.95, top_k 20 and presence_penalty 0, which is a reasonable starting point
  5. The MLX 4-bit build needs UkisAI's patched MLX-LM and has no image or video chat
  6. Check the licence before commercial use, it stops at US$1M gross annual revenue including affiliates
  7. MTP self-speculative decoding is available with the base's head, flags on the card

Questions

Which is better for AI agents, gpt-oss-120b or Swift 1.5 Qwen3.8-27B?

gpt-oss-120b scores 70.2 (BB) on agent readiness against Swift 1.5 Qwen3.8-27B's 61 (C), and leads in 3 of 4 scored categories. Swift 1.5 Qwen3.8-27B leads on reach.

Other comparisons with gpt-oss-120b or Swift 1.5 Qwen3.8-27B

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