[GH-ISSUE #14326] feat: Allow Arenas to use Native Function Calling by default #55878

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GiteaMirror · 2026-05-05T18:12:26-05:00

GiteaMirror commented

2026-05-05 18:12:26 -05:00

Originally created by @ciejer on GitHub (May 26, 2025).
Original GitHub issue: https://github.com/open-webui/open-webui/issues/14326

Check Existing Issues

I have searched the existing issues and discussions.

Problem Description

When adding a model with Tools (via mcpo) defaulted on in the model config as shown below, and 'Native' selected for function calling in advanced parameters, selecting that model in a new chat works perfectly.
However, when adding that model to an arena, the arena does not use the model's tools, and does not use Native function calling.

Steps followed:

Added an MCPO server to OpenWebUI, and ensured the tools work correctly when manually selected.
Created a new model in Workspace, with Function Calling Native, and enabled specific Tools to be on by default.
Opened the model in a New Chat, and queried it to confirm that the tools worked with no further configuration required.
Created a new Arena, and added the model from step 2.
Opened the arena in a New Chat, and queried it; but the tools did not work.
Troubleshooting determined that turning on Function Calling Native, and manually selecting Tools, resulted in the arena working for just the current chat; but a new chat requires these steps to be performed again.

Thank you for your great work!

Desired Solution you'd like

All defaults set in a model config, including Function Calling and selected Tools, should remain when using that model in an Arena.
If specific settings are set in the chat window of an Arena, this should override default settings; but if they have not been set the default settings from the Model should prevail.

Alternatives Considered

Training all Arena users to set function calling and tools per Conversation.

Additional Context

No response

Originally created by @ciejer on GitHub (May 26, 2025). Original GitHub issue: https://github.com/open-webui/open-webui/issues/14326 ### Check Existing Issues - [x] I have searched the existing issues and discussions. ### Problem Description When adding a model with Tools (via mcpo) defaulted on in the model config as shown below, and 'Native' selected for function calling in advanced parameters, selecting that model in a new chat works perfectly. However, when adding that model to an arena, the arena does not use the model's tools, and does not use Native function calling. Steps followed: 1. Added an MCPO server to OpenWebUI, and ensured the tools work correctly when manually selected. 2. Created a new model in Workspace, with Function Calling Native, and enabled specific Tools to be on by default. 3. Opened the model in a New Chat, and queried it to confirm that the tools worked with no further configuration required. 4. Created a new Arena, and added the model from step 2. 5. Opened the arena in a New Chat, and queried it; but the tools did not work. 6. Troubleshooting determined that turning on Function Calling Native, and manually selecting Tools, resulted in the arena working for just the current chat; but a new chat requires these steps to be performed again. Thank you for your great work! ![Image](https://github.com/user-attachments/assets/d017772d-016d-41e4-89f8-56feb461230c) ### Desired Solution you'd like All defaults set in a model config, including Function Calling and selected Tools, should remain when using that model in an Arena. If specific settings are set in the chat window of an Arena, this should override default settings; but if they have not been set the default settings from the Model should prevail. ### Alternatives Considered Training all Arena users to set function calling and tools per Conversation. ### Additional Context _No response_

GiteaMirror closed this issue

2026-05-05 18:12:28 -05:00

GiteaMirror commented

2026-05-05 18:12:34 -05:00

@ejames730 commented on GitHub (Aug 26, 2025):

Have you found any alternative options? I'm in a similar situation where I want to have an arena model use 2 workspace models that have some RAG and knowledge applied to them. I've found that when I add the 2 workspace ones that I modified the system prompt to those get ignored. It's like running the base models directly.

@ejames730 commented on GitHub (Aug 26, 2025): Have you found any alternative options? I'm in a similar situation where I want to have an arena model use 2 workspace models that have some RAG and knowledge applied to them. I've found that when I add the 2 workspace ones that I modified the system prompt to those get ignored. It's like running the base models directly.

GiteaMirror commented

2026-05-05 18:12:38 -05:00

@ciejer commented on GitHub (Aug 26, 2025):

Nope - we're now using user tools and a filter function to achieve our a/b testing as the native arenas were not usable for our requirements.

@ciejer commented on GitHub (Aug 26, 2025): Nope - we're now using user tools and a filter function to achieve our a/b testing as the native arenas were not usable for our requirements.

GiteaMirror commented

2026-05-05 18:12:41 -05:00

@ejames730 commented on GitHub (Aug 27, 2025):

Thanks I'll look into that.

@ejames730 commented on GitHub (Aug 27, 2025): Thanks I'll look into that.

GiteaMirror commented

2026-05-05 18:12:42 -05:00

@tjbck commented on GitHub (Feb 22, 2026):

#20658

@tjbck commented on GitHub (Feb 22, 2026): #20658

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