I've been defaulting to Opus-tier or GPT-5.5 for anything agent-related because that felt like the safe call. Better reasoning, better tool use, better outcomes. Flash-tier models were for batch jobs, summaries, things where you didn't care that much about output quality. That calculus broke for me after spending time with the Gemini 3.5 Flash benchmarks . The model went GA on May 19 at Google I/O. The number that got my attention: 83.6% on MCP Atlas, a benchmark specifically for multi-step tool orchestration using Model Context Protocol servers. That puts it 8.3 points ahead of GPT-5.5 (75.3%) and 4.5 points ahead of Claude Opus 4.7 on the same eval. "Flash" doesn't mean what it used to. What MCP Atlas Is Actually Measuring MCP Atlas tests whether a model can chain together multiple tool calls across MCP servers, recover from partial failures, and complete multi-step tasks without going off-script. It's not a writing or reasoning benchmark. If you're ...