feat(prompt): encourage markdown formatting in AI responses

prompts/default/agent.system.tool.response.md

@@ -3,6 +3,7 @@ final answer to user
 ends task processing use only when done or no task active
 put result in text arg
 always write full file paths
+always use markdown for formatting including headers bold text and lists to improve readability
 usage:
 ~~~json
 {