Forum Discussion

ArneVG's avatar
ArneVG
Copper Contributor
Apr 23, 2026

Failed to add tool to agent - Preview Feature Required?

Hi, We’ve recently run into an issue where we’re no longer able to add tools to our Foundry agent. This was previously working without problems in our development environment, but now every attempt ...
azure ai foundry
Surya_Narayana's avatar
Surya_Narayana
MCT
Apr 25, 2026

hi ArneVG​ The 403 combined with the AgentEndpoints=V1Preview message does suggest this is likely related to a preview feature requirement rather than a normal permissions issue.

It looks like Microsoft may have recently moved some Foundry agent tool functionality behind an opt-in preview flag/API header. In many cases, these preview features are:

Region/environment dependent

Subscription/tenant gated

Gradually rolled out

If you’re using SDK/API calls, the request may now require the header:

Foundry-Features: AgentEndpoints=V1Preview

If this is happening through the portal/UI, then the backend service itself may not yet be enabled for your tenant/environment.

I’d recommend:

Checking the latest Azure AI Foundry preview documentation/release notes

Verifying the environment/region supports the preview

Opening a Microsoft support ticket, since 403 can also indicate the feature is not enabled server-side for your tenant

The behavior does sound like a recent backend/platform change rather than something wrong in your implementation.