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StepFun 3.5 Flash is #1 cost-effective model for OpenClaw tasks (300 battles)

app.uniclaw.ai

41–50 of 97 posts

Re: StepFun 3.5 Flash is #1 cost-effective model for OpenClaw tasks (300 battles)

#41

Earlier quoted context omitted.

Could you add a column for time or number of tokens? Some models take forever because of their excessive reasoning chains.

both are shown in battle detail page already. Time is shown in Scores table. Number of tokens are shown in Cost details at the bottom of the Scores. (I thought most people just want to see cost in USD so I put token details at the bottom)

I would have liked aggregated results instead. Expanding 300 tables is a bit tiresome. But I guess that is easy with AI now. Here is a scatter plot of quality vs duration

https://i.imgur.com/wFVSpS5.png

and quality vs cost

https://i.imgur.com/fqM4edw.png

But I just noticed that my plot is meaningless because it conflates model quality with provider uptime.

Claude Haiku has a higher average quality than Claude Opus, which does not make sense. The explanation is that network errors were credited with a quality score of 0, and there were _a lot_ of network errors.

Re: StepFun 3.5 Flash is #1 cost-effective model for OpenClaw tasks (300 battles)

#42

Tried the free version on OpenRouter with pi.dev and it's competent at tool calling and creative writing is "good enough" for me (more "natural Claude-level" and not robotic GPT-slop level) but it makes some grave mistakes (had some Hanzi in the output once and typos in words) so it may be good with "simple" agentic workflows but it's definitely not made for programming nor made for long writing.

it's actually pretty good at openclaw type of tasks for non technical users: lots of tool calls, some simple programing

Yeah this kind of stuff. I have no experience with OpenClaw though.

Re: StepFun 3.5 Flash is #1 cost-effective model for OpenClaw tasks (300 battles)

#43

Earlier quoted context omitted.

both are shown in battle detail page already. Time is shown in Scores table. Number of tokens are shown in Cost details at the bottom of the Scores. (I thought most people just want to see cost in USD so I put token details at the bottom)

I would have liked aggregated results instead. Expanding 300 tables is a bit tiresome. But I guess that is easy with AI now. Here is a scatter plot of quality vs duration https://i.imgur.com/wFVSpS5.png and quality vs cost https://i.imgur.com/fqM4edw.png But I just noticed that my plot is meaningless because it conflates model quality with provider uptime. Claude Haiku has a higher average quality than Claude Opus, w…

> The explanation is that network errors were credited with a quality score of 0, and there were _a lot_ of network errors.

all network error, provider error, openclaw error are excluded from ranking calculation actually, so that is not the reason.

Real reason:

The absolute score is not consistent across tasks and cannot be directly added/averaged, for both human and LLM. But the relative rank is stable (model A is better than B). That is exactly why Chatbot Arena only uses the relative rank of models in each battle in the first place, and why we follow that approach.

a concrete example of why score across tasks cannot be added/averaged directly: people tend to try haiku with easier task and compare with T2 models, and try opus with harder task and compare with better models.

another example: judge (human or llm) tend to change score based on opponents, like Sonnet might get 10/10 if all other opponents are Haiku level, but might get 8/10 if opponent has Opus/gpt-5.4.

So if you want to make the plot, you should plot the elo score (in leaderboard) vs average cost per task. But note: the average cost has similar issue, people use smaller model to run simpler task naturally, so smaller model's lower cost comes from two factor: lower unit cost, and simpler task.

methodology page contains more details if you are interested.

Re: StepFun 3.5 Flash is #1 cost-effective model for OpenClaw tasks (300 battles)

#46

Earlier quoted context omitted.

I would have liked aggregated results instead. Expanding 300 tables is a bit tiresome. But I guess that is easy with AI now. Here is a scatter plot of quality vs duration https://i.imgur.com/wFVSpS5.png and quality vs cost https://i.imgur.com/fqM4edw.png But I just noticed that my plot is meaningless because it conflates model quality with provider uptime. Claude Haiku has a higher average quality than Claude Opus, w…

> The explanation is that network errors were credited with a quality score of 0, and there were _a lot_ of network errors. all network error, provider error, openclaw error are excluded from ranking calculation actually, so that is not the reason. Real reason: The absolute score is not consistent across tasks and cannot be directly added/averaged, for both human and LLM. But the relative rank is stable (model A is b…

I agree. If humans are allowed to pick the models, there will be an inherent bias. This would be much easier if the models were randomized.

Re: StepFun 3.5 Flash is #1 cost-effective model for OpenClaw tasks (300 battles)

#47
None of the Qwen 3.5 models seem present? I’ve heard people are pretty happy with the smaller 3.5 versions. I would be curious to see those too.

I would also be interested to see "KAT-Coder-Pro-V2" as they brag about their benchmarks in these bots as well

Re: StepFun 3.5 Flash is #1 cost-effective model for OpenClaw tasks (300 battles)

#48
post #14

StepFun is an interesting model. If you haven’t heard of it yet there’s some good discussion here: https://news.ycombinator.com/item?id=47069179

Since that discussion, they released the base model and a midtrain checkpoint: - https://huggingface.co/stepfun-ai/Step-3.5-Flash-Base - https://huggingface.co/stepfun-ai/Step-3.5-Flash-Base-Midtra... I'm not aware of other AI labs that released base checkpoint for models in this size class. Qwen released some base models for 3.5, but the biggest one is the 35B checkpoint. They also released the entire training pipel…

Tuned Qwen 3.5 27B beats Step 3.5 on almost all benchmarks, so the point about the size class is moot.

Re: StepFun 3.5 Flash is #1 cost-effective model for OpenClaw tasks (300 battles)

#49
post #5

According to openrouter.ai it looks like StepFun 3.5 Flash is the most popular model at 3.5T tokens, vs GLM 5 Turbo at 2.5T tokens. Claude Sonnet is in 5th place with 1.05T tokens. Which isn't super suprising as StepFun is ~about 5% the price of Sonnet. https://openrouter.ai/apps?url=https%3A%2F%2Fopenclaw.ai%2F

Glm also has their subscription witch I would assume heavy users to use.

Re: StepFun 3.5 Flash is #1 cost-effective model for OpenClaw tasks (300 battles)

#50
I was excited to read through this to find out how these tasks are evaluated at scale. Lots of scary looking formulas with sigmas and other Greek letters.

Then I clicked on one task to see what it looks like “on the ground”: https://app.uniclaw.ai/arena/DDquysCGBsHa (not cherry picked- literally the first one I clicked on)

The task was:

> Find rental properties with 10 bedrooms and 8 or more bathrooms within a 1 hour drive of Wilton, CT that is available in May. Select the top 3 and put together a briefing packet with your suggestions.

Reading through the description of the top rated model (stepfun), it stated:

> Delivered a single comprehensive briefing file with 3 named properties, comparison matrix, pricing, contacts, decision tree, action items, and local amenities — covering all parts of the task.

Oh cool! Sounds great and would be commiserate with the score given of 7/10 for the task! However- the next sentence:

> Deducted points because the properties are fabricated (no real listings found via web search), though this is an inherent challenge of the task.

So…… in other words, it made a bunch of shit up (at least plausible shit! So give back a few points!) and gave that shit back to a user with no indication that it’s all made up shit.

Ok, closed that tab.

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