fix: Missing final structured output should provide guidance to model (#4654)

crates/goose/src/agents/agent.rs

@@ -1308,6 +1308,7 @@ impl Agent {
                             let message = Message::user().with_text(FINAL_OUTPUT_CONTINUATION_MESSAGE);
                             messages_to_add.push(message.clone());
                             yield AgentEvent::Message(message);
+                            messages.extend(messages_to_add);
                             continue
                         } else {
                             let message = Message::assistant().with_text(final_output_tool.final_output.clone().unwrap());

crates/goose/src/agents/final_output_tool.rs

@@ -38,17 +38,17 @@ impl FinalOutputTool {
 
     pub fn tool(&self) -> Tool {
         let instructions = formatdoc! {r#"
-            This tool collects the final output for a user and provides validation for structured JSON final output against a predefined schema.
+            The final_output tool collects the final output for the user and provides validation for structured JSON final output against a predefined schema.
 
-            This tool MUST be used for the final output to the user.
+            This final_output tool MUST be called with the final output for the user.
             
             Purpose:
-            - Collects the final output for a user
+            - Collects the final output for the user
             - Ensures that final outputs conform to the expected JSON structure
             - Provides clear validation feedback when outputs don't match the schema
             
             Usage:
-            - Call the `final_output` tool with your JSON final output
+            - Call the `final_output` tool with your JSON final output passed as the argument.
             
             The expected JSON schema format is:
 
@@ -83,8 +83,8 @@ impl FinalOutputTool {
         formatdoc! {r#"
             # Final Output Instructions
 
-            You MUST use the `final_output` tool to collect the final output for a user.
-            The final output MUST be a valid JSON object that matches the following expected schema:
+            You MUST use the `final_output` tool to collect the final output for the user rather than providing the output directly in your response.
+            The final output MUST be a valid JSON object that is provided to the `final_output` tool when called and it must match the following schema:
 
             {}