Grok vs Opus 4.8

What I tested — same prompt, two models

I run the same fixed prompt set through every new model the day it drops — same string, one shot, single HTML file out — and I score the result 0–10 on whether it ran, how close it hit the brief, and how good it looked. Below is what came out when I gave the exact same prompts to Grok and Opus 4.8, side by side, on 47 shared tasks inside the Agent Operating System.

Both models were given identical prompts inside the Agent Operating System — no help, no iteration, no "best of N" tricks. I run each prompt once, save the HTML file the model produces, and score it 0–10 on whether it ran, how close it hit the brief, and how good it looked. The scoring is mine. The verdicts below are pulled from my source comparison guides at agentos.guide where I publish every score and the reasoning behind it.

Grok · Used for real-time content workflows where the model needs current X timeline context. Standalone bench scoring pending.

Opus 4.8 · The default when the build has to ship on the first prompt — Opus is the safety net inside Agent OS for hard one-shots.

Where Grok beat Opus 4.8

The tasks where I gave Grok a higher 0–10 score on the same prompt — with the actual commentary from my source guides.

Where Opus 4.8 beat Grok

The tasks where I gave Opus 4.8 a higher 0–10 score on the same prompt — with the actual commentary from my source guides.

Strengths & weaknesses I logged

Pricing & context — the spec sheet

The verdict — which should you pick?

Across 43 scored shared tasks, Grok averaged 8.09/10, beating Opus 4.8's 7.60/10 by 0.49 points. Pick Grok when the build has to ship on the first prompt and you can afford the trade-offs in the comparison below.

If you only run one of these inside your stack, the head-to-head average above is the call. If you can run both, my honest play is to wire Grok and Opus 4.8 both into the Agent Operating System and dispatch each from the kanban by task type — workflows that need live x / twitter context → Grok, mission-critical one-shot builds where 'has to work the first time' matters → Opus 4.8. That's the same setup I run for the 4,000+ founders inside the AI Profit Boardroom.

FAQ — Grok vs Opus 4.8

Which is better, Grok or Opus 4.8?

On Goldie Bench, Grok averages 8.09/10 across the shared tasks, with 5 gold, 1 silver, 1 bronze overall. Opus 4.8 averages 7.60/10, with 3 gold, 1 silver, 1 bronze. Grok wins the head-to-head 22–8.

How much does Grok cost vs Opus 4.8?

Grok: Bundled with X (Twitter) Premium subscription — no per-token bill for end users, no individual API pricing for the chat product. Opus 4.8: Premium pricing via the Anthropic API: $15 per million input tokens, $75 per million output tokens. Extended thinking is included but adds latency.

What's the context window for Grok vs Opus 4.8?

Grok has a 256,000 tokens context window. Opus 4.8 has a 200,000 tokens (1M with extended thinking) context window.

When should I pick Grok over Opus 4.8?

Pick Grok for: Workflows that need live X / Twitter context; Snappy prompts where latency matters; Researchers comparing X-native models against the rest of the field. The trade-off is the weaknesses we logged on the bench: 13 demos on the bench but zero have curated 0–10 verdicts yet — currently unranked; API access is gated behind X Premium, awkward for backend agent loops.

When should I pick Opus 4.8 over Grok?

Pick Opus 4.8 for: Mission-critical one-shot builds where 'has to work the first time' matters; Hard reasoning tasks (planning, multi-step) where you'll pay for the depth; Anything where vendor reliability beats the per-token bill. The trade-off is the weaknesses we logged on the bench: 5–10× the per-token cost of every other model on the bench; Less flair on cinematic visuals than GLM-5.2 — playing it safer wins on accuracy, costs you on showpiece moments.

How does Goldie Bench score Grok vs Opus 4.8?

Every demo on this page was built by Julian Goldie inside the Agent Operating System — same fixed prompt for both models, one shot, single HTML file out. Each result gets a 0–10 score on whether it ran, how close it hit the brief, and how good it looked. The highest score on each task gets gold; second gets silver; third gets bronze. See methodology for full provenance.

Related comparisons

Other head-to-heads using the same scoring system:

Full model pages: Grok · Opus 4.8 · back to the leaderboard