I found the way to get the token count

CompletionTokens = assistantClient.GetRuns(threadID).Select(f => f.Usage.CompletionTokens).SingleOrDefault(); PromptTokens = assistantClient.GetRuns(threadID).Select(f => f.Usage.PromptTokens).SingleOrDefault(); TotalTokens = assistantClient.GetRuns(threadID).Select(f => f.Usage.TotalTokens).SingleOrDefault();