Kimi K3 and Fable Route Strategy Achieve 93% Accuracy with Cost Reduction of Up to 50x

ChainCatcher report: Fireworks AI released an evaluation report comparing the open-source model Kimi K3 with the proprietary model Fable 5 across approximately 1,030 agent tasks spanning SWE, terminal operations, algorithms, multilingual coding, legal scenarios, and more. Results showed both models achieved nearly identical accuracy rates on the SWE benchmark—92.4% for K3 and 92.6% for Fable—with each excelling in specific subdomains: K3 outperformed in symbolic mathematics and development tools, while Fable demonstrated superior performance in web and data visualization tasks. In long-duration terminal tasks, K3 independently solved 11 tasks that Fable could not complete. The report notes that implementing a task-level routing strategy dynamically allocates tasks between the two models, achieving 93% overall accuracy—surpassing either model alone. Additionally, due to K3’s significant cost advantage on the Fireworks platform, its operational cost for long-duration agent tasks can be up to 50 times lower than Fable’s. The report recommends using the open-source model as the default option, leveraging a router that continuously learns optimal task-to-model pairings to balance performance and cost efficiency.