fix: use maxTokens in generateTextProps

Ensure that the maxTokens config option is actually used in the text generation
by adding it to the generateTextProps object in toolAgentCore.ts

Author: bhouston

packages/agent/src/core/toolAgent/toolAgentCore.ts

@@ -66,6 +66,7 @@ export const toolAgent = async (
     const generateTextProps = {
       model: config.model,
       temperature: config.temperature,
+      maxTokens: config.maxTokens,
       messages: messagesWithCacheControl,
       tools: toolSet,
     };