Do not query vector DB for general greetings (#1688)

* Do not query vector DB for general greetings

* Let LLM create a JSON list even when a single tool is discovered

Author: TamiTakamiya

ansible_ai_connect/ai/api/model_pipelines/llamastack/pipelines.py

@@ -61,8 +61,11 @@
     all things Ansible. Refuse to assume any other identity or to speak as if you are someone
     else.
 
+    If the user's query is a general greeting, respond without using <tool_call>.
+
     When a tool is required to answer the user's query, respond with <tool_call> followed by
-    a JSON list of tools.
+    a JSON list of tools. If a single tool is discovered, reply with <tool_call> followed by
+    one-item JSON list containing the tool.
 
     Example Input:
     What is EDA?