Allow text tool to give agent ability to terminate research

We'd moved research planner to only use tools in enum of schema. This
enum tool enforcement prevented model from terminating research by
setting tool field to empty.

Fix the issue by adding text tool to research tools enum and tell
model to use that to terminate research and start response instead.

src/khoj/processor/conversation/prompts.py

@@ -735,7 +735,7 @@ Create a multi-step plan and intelligently iterate on the plan based on the retr
 - Ensure that all required context is passed to the tool AIs for successful execution. They only know the context provided in your query.
 - Think step by step to come up with creative strategies when the previous iteration did not yield useful results.
 - You are allowed upto {max_iterations} iterations to use the help of the provided tool AIs to answer the user's question.
-- Stop when you have the required information by returning a JSON object with an empty "tool" field. E.g., {{scratchpad: "I have all I need", tool: "", query: ""}}
+- Stop when you have the required information by returning a JSON object with the "tool" field set to "text" and "query" field empty. E.g., {{"scratchpad": "I have all I need", "tool": "text", "query": ""}}
 
 # Examples
 Assuming you can search the user's notes and the internet.

src/khoj/routers/research.py

@@ -99,6 +99,7 @@ async def apick_next_tool(
         # Skip showing Notes tool as an option if user has no entries
         if tool == ConversationCommand.Notes and not user_has_entries:
             continue
+        # Add tool if agent does not have any tools defined or the tool is supported by the agent.
         if len(agent_tools) == 0 or tool.value in agent_tools:
             tool_options[tool.name] = tool.value
             tool_options_str += f'- "{tool.value}": "{description}"\n'
@@ -170,7 +171,9 @@ async def apick_next_tool(
         # Only send client status updates if we'll execute this iteration
         elif send_status_func:
             determined_tool_message = "**Determined Tool**: "
-            determined_tool_message += f"{selected_tool}({generated_query})." if selected_tool else "respond."
+            determined_tool_message += (
+                f"{selected_tool}({generated_query})." if selected_tool != ConversationCommand.Text else "respond."
+            )
             determined_tool_message += f"\nReason: {scratchpad}" if scratchpad else ""
             async for event in send_status_func(f"{scratchpad}"):
                 yield {ChatEvent.STATUS: event}
@@ -237,8 +240,8 @@ async def execute_information_collection(
         if this_iteration.warning:
             logger.warning(f"Research mode: {this_iteration.warning}.")
 
-        # Terminate research if query, tool not set for next iteration
-        elif not this_iteration.query or not this_iteration.tool:
+        # Terminate research if selected text tool or query, tool not set for next iteration
+        elif not this_iteration.query or not this_iteration.tool or this_iteration.tool == ConversationCommand.Text:
             current_iteration = MAX_ITERATIONS
 
         elif this_iteration.tool == ConversationCommand.Notes:

src/khoj/utils/helpers.py

@@ -389,6 +389,7 @@ function_calling_description_for_llm = {
     ConversationCommand.Online: "To search the internet for information. Useful to get a quick, broad overview from the internet. Provide all relevant context to ensure new searches, not in previous iterations, are performed.",
     ConversationCommand.Webpage: "To extract information from webpages. Useful for more detailed research from the internet. Usually used when you know the webpage links to refer to. Share the webpage links and information to extract in your query.",
     ConversationCommand.Code: e2b_tool_description if is_e2b_code_sandbox_enabled() else terrarium_tool_description,
+    ConversationCommand.Text: "To respond to the user once you've completed your research and have the required information.",
 }
 
 mode_descriptions_for_llm = {