On: Opus 4.5 is not the normal AI agent experience that I have had thus far

[ern]

I have been out of the loop for a couple of months (vacation). I tried Claude Opus 4.5 at the end of November 2025 with the corporate Github Copilot subscription in Agent mode and it was awful: basically ignoring code and hallucinating.

My team is using it with Claude Code and say it works brilliantly, so I'll be giving it another go.

How much of the value comes from Opus 4.5, how much comes from Claude Code, and how much comes from the combination?

[everfrustrated → ern]

As someone coming from GitHub copilot in vscode and recently trying Claude Code plugin for vscode I don't get the fuss about Claude.

Copilot has by far the best and most intuitive agent UI. Just make sure you're in agent mode and choose Sonnet or Opus models.

I've just cancelled my Claude sub and gone back and will upgrade to the GH Pro+ to get more sonnet/opus.

[indigodaddy → everfrustrated]

Check out Antigravity+Google AI Pro $20 plan+Opus 4.5. apparently the Opus limits are insanely generous (of course that could change on a dime).

[pluralmonad → everfrustrated]

I strongly concur with your second statement. Anything other than agent mode in GH copilot feels useless to me. If I want to engage Opus through GH copilot for planning work, I still use agent mode and just indicate the desired output is whatever.md. I obviously only do this in environments lacking a better tool (Claude Code).

[ern → everfrustrated]

I'd used both CC and Copilot Agent Mode in VSCode, but not the combination of CC + Opus 4.5, and I agree, I was happy enough with Copilot.

The gap didn't seem big, but in November (which admittedly was when Opus 4.5 was in preview on Copilot) Opus 4.5 with Copilot was awful.

[Dusseldorf → ern]

I suspect that's the other thing at play here; many people have only tried Copilot because it's cheap with all the other Microsoft subscriptions many companies have. Copilot frankly is garbage compared to Cursor/Claude, even with the same exact models.