Kimi K3 and Claude Fable 5 aren’t just strong models by themselves. Per-task model routing lets an agent send the right work to the right model, hitting very high accuracy while cutting cost versus using Fable alone—largely thanks to how tokens, turns, and prompt caching behave in long loops.
Kimi K3 is Moonshot AI’s open 2.8T-parameter multimodal model with a 1M-token context window. Built on KDA and Attention Residuals, plus stable MoE expert routing, it’s positioned as a frontier-capable open-weight system—especially for long-horizon coding and even GPU kernel/compiler workflows.
Kimi K3 is now available through the Kimi API as a reasoning-first, multimodal model with a 1M-token context window. This guide shows the OpenAI-SDK style integration, streaming behavior, strict JSON schema outputs, vision message formatting, and a correct tool-calling loop.