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.NET: Azure AI Projects agent-mode silently ignores per-request tools (AG-UI/ChatOptions.Tools) #2959
Description
Summary
When using [AIProjectClient.CreateAIAgentAsync(...)]. During runs, tools provided per request (e.g., via AG-UI frontend tool definitions) are silently dropped and never reach the model/service request. This makes AG-UI “frontend tools” unusable with Azure AI Projects agents unless they were baked into the server-side agent definition at creation/version time.
Why this matters
AG-UI expects to be able to provide tool definitions per request (especially client-side / frontend tools).
Today this fails silently: the agent runs, but never calls/uses the provided tools because the model never sees them.
The silent ignore is hard to diagnose and looks like “tools don’t work”.
The per-request tools never show up in the model request context, so the agent never calls them.
No error/warning is produced.
Expected behavior (pick one)
Option A (strict): If per-request tools are supplied in agent-mode, explaining they are not supported and that tools must be added to the server-side agent definition/version.
Option B (support): Allow per-request tool augmentation (union) so AG-UI frontend tools work with agent-mode.
Root cause / code pointers
The Azure AI Projects agent-mode client intentionally clears non-overridable options in GetAgentEnabledChatOptions.
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[-]Azure AI Projects agent-mode silently ignores per-request tools (AG-UI/ChatOptions.Tools)[/-][+].NET: Azure AI Projects agent-mode silently ignores per-request tools (AG-UI/ChatOptions.Tools)[/+]MaciejSzczepanskiRedslim commentedon Jan 21, 2026
I've just noticed this PR #3285 - so it sounds like if you want to use AG-UI + frontend tools, then don't use foundry agents.... Mark Wallace (@markwallace-microsoft) ?
simonscoffins commentedon Feb 2, 2026
Maciek (@MaciejSzczepanskiRedslim) This is something I have been struggling with that I thought would be carried over from the "Classic Foundry" to the "New Foundry" (NF).
Right now in NF I can create an agent to user the code interpreter tool but I cannot upload a file for a specific conversation other than a pdf for the agent to analyze (tested). So if I want to create a UI for an agent to analyze a file csv on a request basis I have to convert the csv file to pdf first...
Loading a csv at agent creation time makes the data available to all calls to the agent. This is probably going to stop us moving forward using Foundry Agents at this moment.
Or am I missing something fundamental? More than happy to be corrected and pointed in the right direction.
Does anyone have an alternative approach to Agent + UI + File Upload + Tool request?
javiercn commentedon Aug 18, 2026
I checked the current Foundry Agent Service documentation, and this limitation has not been lifted.
A service-managed
FoundryAgentuses the model, instructions, and tools stored in its Foundry agent definition. Per-runtools,tool_choice, andparallel_tool_callsare removed from the request because the client cannot add model-visible tools dynamically.For AG-UI frontend tools, the supported approach is therefore to preregister the corresponding function definitions—using matching names and schemas—on the Foundry agent definition/version. AG-UI can then surface calls to those functions for execution by the frontend.
If the available tools must change dynamically per request, use an application-owned
FoundryChatClientinstead of a service-managed Foundry agent. The current documentation explicitly recommends that model when runtime tool selection is required:https://learn.microsoft.com/agent-framework/integrations/by-component/agent-services/foundry#connect-to-a-prompt-agent
Supporting dynamic tools on service-managed agents would require a Foundry Agent Service capability. Please raise that scenario through the Foundry Agent Service or Azure SDK feedback channels.
Since Agent Framework cannot forward per-request tools where the underlying service-managed agent contract does not support them, I’m closing this issue.