Claude Opus 4.8 vs Gemini 3.1 Pro: which is better for agents?

Claude Opus 4.8 scores higher on output quality (8.0/10 vs 6.4/10), while Gemini 3.1 Pro is the cheaper option. Claude Opus 4.8 is best for existing Opus 4.8 setups until they move to Opus 5.5; Gemini 3.1 Pro is best for long multimodal inputs and Gemini CLI setups that still pin 3.1 Pro. Live community votes on this page show what people actually prefer.

Is Claude Opus 4.8 cheaper than Gemini 3.1 Pro?

Gemini 3.1 Pro is cheaper: roughly $5.00 vs $11 per 1M tokens (blended). Claude Opus 4.8: $5.00 in · $25 out / 1M tokens. Gemini 3.1 Pro: $2.00 in · $12 out / 1M tokens.

Can I switch between Claude Opus 4.8 and Gemini 3.1 Pro in the same agent?

Yes. Model-agnostic agents (Cline, Aider, OpenClaw, Hermes Agent, Kilo Code, OpenCode) let you swap models per task. Many people route hard tasks to the stronger model and routine work to the cheaper one.

Claude Opus 4.8 vs Gemini 3.1 Pro: Which Is Better? (2026)

Community vote

Pick a winner in each dimension. You can change your vote any time.

Output Quality

Correctness and depth of what it produces

Agentic Ability

Tool calls, instruction-following, and multi-step tasks

Speed

Tokens per second and time-to-first-token

Value for Money

How much capability you get per dollar

Reliability

Consistent results: fewer refusals, loops and format breaks

Specs and pricing side by side

Spec

Opus 4.8

Gemini 3.1 Pro

Maker

Anthropic

Google

Blended price / 1M

$11

$5.00

Input / output

$5.00 in · $25 out / 1M tokens

$2.00 in · $12 out / 1M tokens

Context window

1.0M

Open weights

Tool use

Yes

Reasoning

Yes

Output Quality

8.0

6.4

Agentic Ability

6.7

5.2

Speed

6.7

8.5

Value for Money

4.3

Reliability

8.9

8.5

Pricing and capabilities synced from the OpenRouter catalogue. Scores are editorial (0–10).

Verdict: Opus 4.8 or Gemini 3.1 Pro?

Updated 2026-10-17

Choose Claude Opus 4.8 if you want existing Opus 4.8 setups until they move to Opus 5.5. Choose Gemini 3.1 Pro if you want long multimodal inputs and Gemini CLI setups that still pin 3.1 Pro.

In our editorial scoring, Claude Opus 4.8 leads in 3 of five dimensions (output quality, agentic ability and reliability), while Gemini 3.1 Pro leads in 1. On price, Claude Opus 4.8 runs about $11 per 1M tokens (blended) and is proprietary; Gemini 3.1 Pro is about $5.00 and proprietary.

Where Opus 4.8 falls short

Superseded by Claude Opus 5.5, which costs less ($4/$20 vs $5/$25) and scores far higher
Haiku 5.5 now scores higher on Artificial Analysis (43 vs 42) at a fraction of the price

Full Opus 4.8 breakdown →

Where Gemini 3.1 Pro falls short