> For example, when we served Kimi K2.6 with vLLM version 0.28, we got the expected tool call schema only 92% of the time. In other words, 2 out of every 25 attempted tool calls failed.

100% success is critical for tool calling.

The probability that the overall agent iteration is successful would scale very poorly even if we achieved 95%. With p95, if you need 50 tool calls that must execute sequentially to achieve a result, the chances that you won't have an error are only ~8%. There are ways to recover from bad tool calls (error feedback helps a lot), but if the agent is persistently using the wrong tools with the wrong args the overall system will not work very well.