Grok 4.20 Multi-Agent vs GPT-5.6 Luna

xAI Grok 4.20 Multi-AgentOpenAI GPT-5.6 Luna
VendorxAIOpenAI
Context window2,048,0001,050,000
Max output1,000,000128,000
ReasoningYesYes
Tool callingYesYes
File inputYesYes
Inputtext, imagetext, image
Outputtexttext
Released2026-03-082026-07-08