Announced last month:

https://devblogs.microsoft.com/dotnet/introducing-microsoft-extensions-ai-preview/

Sentry's Agent monitoring docs: https://docs.sentry.io/product/insights/agents/

SDK docs: https://develop.sentry.dev/sdk/telemetry/traces/modules/ai-agents/

Example API:

app.Services.AddChatClient(builder => builder 
    // Add Sentry LLM monitoring
    .UseSentry()    
    .Use(new OpenAIClient(...)).AsChatClient(...)); 

In a new package named: Sentry.Extensions.AI

https://www.nuget.org/packages/Microsoft.Extensions.AI.Abstractions/#versions-body-tab
Seems this one didn't leave preview though.