Claude Sonnet 5.5 vs Gemini 4 Argon

$0.88 / task
Wins 0 of 3 benchmarks
$1.99 / task
Wins 2 of 3 benchmarks
Arena Text · creative writing Arena Text · creative writing: Human pairwise preferences in the stated text vote pool
Sonnet 5.5 · xhigh1,465
Gemini 4 Argon1,516
Harvey LAB-AA 1.1 Harvey LAB-AA 1.1: Legal agents work from case documents; every rubric criterion must pass and material hallucinations receive no credit
Sonnet 5.5 · max2.8
Gemini 4 Argon3.9
Lech Mazur Short-Story Lech Mazur Short-Story · comparison score: Judges compare stories written to ten required elements; the comparison score can be negative
Sonnet 5.5—
Gemini 4 Argon0.8

Specs

SpecSonnet 5.5Gemini 4 Argon
Input, per 1M$2!$2
Output, per 1M$10!$10
Cost per task?$0.88$1.99
Speed, tok/s10684
Context1M1M
WeightsClosedClosed
ReleasedSep 2026Oct 2026
See images✓✓
Read PDFs✓✓
Hear audio—✓
Watch video—✓
Call tools✓✓
Force a tool call—Partial
Return strict JSON✓✓
Search the web✓✓
Run code✓✓
Use a computer✓?

What breaks when you switch

Sonnet 5.5 → Gemini 4 Argon
Synchronous output stops at 65,536›

With background false, output limits above 65,536 tokens return HTTP 400; stay at or below that limit.

Sampling parameters are ignored›

temperature, top_p and top_k are ignored; remove them from requests.

No explicit caching›

Explicit caching is unavailable; omit explicit cache requests.

Gemini 4 Argon → Sonnet 5.5
No forced tool use›

Forced tool_choice any or tool returns HTTP 400; remove the forced choice.

Replace disabled thinking›

Disabled thinking returns HTTP 400; use between_tools for the lowest thinking setting.

No manual thinking budgets›

Manual thinking budgets and extra between_tools fields return HTTP 400; remove manual budgets and send between_tools without display, budget_tokens or block_binding.

Remove sampling parameters›

Non-default temperature, top_p or top_k returns HTTP 400; remove these parameters.

No assistant prefill›

A prefilled final assistant turn returns HTTP 400; remove that prefill.

Old computer tool rejected · Claude API / Google Cloud›

The computer_20251124 tool returns HTTP 400 on the Claude API and Google Cloud; use computer_toolset_20260801 there.