DeepSeek's top-ranked V4 Flash stumbles on real agent tasks as its prices surge

DeepSeek's V4 Flash has topped model leaderboards and been hailed by developers as a "total monster" since its rollout. But in real-world testing, it completed just 53.8% of a batch of complex agent tasks. Composio ran the model through eight different agent harnesses, including Claude Code, Codex, and OpenCode, on 30 deliberately difficult, multi-step tasks spanning live tools like Gmail, GitHub, Slack, and Google Sheets. Of 240 total runs, 129 passed — and only six of the 30 workflows were completed successfully by every harness tested.The gap illustrates why orchestration, not raw model capability, may decide whether the model succeeds in enterprise settings: the same model produced substantially different results depending on the harness, tool configuration, caching behavior, retries,