Claude Opus 5.5 vs MiniMax M3.1 Flash

$1.34 / task
Wins 2 of 4 benchmarks
$0.22 / task
Wins 0 of 4 benchmarks
Different efforts: medium · thinking
MMMU-Pro (vision) MMMU-Pro (vision): College-level questions that require understanding images: charts, diagrams, photos
Opus 5.585.7
MiniMax M3.1 Flash79.1
GDP.pdf · AA all-pass GDP.pdf · AA all-pass: Models reason over professional PDF documents; an attempt passes only when every atomic criterion passes
Opus 5.525.6
MiniMax M3.1 Flash20.8
Chartography Chartography: Expert chart reasoning over professional scientific, medical, financial and engineering charts
Opus 5.5 · max66.3
MiniMax M3.1 Flash—
Arena Vision · overall Arena Vision · overall: Human pairwise preferences in the stated vision vote pool
Opus 5.5 · high1,320.8
MiniMax M3.1 Flash—

Specs

SpecOpus 5.5MiniMax M3.1 Flash
Input, per 1M$4$0.15
Output, per 1M$20$0.60
Cost per task?$1.34$0.22
Speed, tok/s81105
Context1M1M
WeightsClosedClosed
ReleasedSep 2026Oct 2026
See images✓✓
Read PDFs✓—
Hear audio——
Watch video—✓
Call tools✓Partial
Force a tool call—?
Return strict JSON✓Partial
Search the web✓?
Run code✓?
Use a computer✓?

What breaks when you switch

Opus 5.5 → MiniMax M3.1 Flash
No PDF input
Complete model response must be appended›

In multi-turn tools, preserve the complete assistant response, including reasoning_content and tool_calls, to maintain reasoning continuity.

MiniMax M3.1 Flash → Opus 5.5
No forced tool use›

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

Thinking is always on›

Disabled thinking or a manual budget returns HTTP 400; omit thinking or use adaptive thinking.

Remove sampling parameters›

Non-default temperature, top_p or top_k returns HTTP 400; omit these parameters and use prompting.

No assistant prefill›

Assistant prefill returns HTTP 400; use structured outputs or system instructions, with system instructions on Bedrock.

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.

Return thinking blocks unmodified›

Edited, reordered or partially dropped thinking blocks return HTTP 400; echo assistant messages complete and unmodified with tool results.