Fix replacing str resp with tool call

agent.py

@@ -14,14 +14,13 @@ import requests
 from pathlib import Path
 from dotenv import load_dotenv
 
-from pydantic import BaseModel, Field
-
 from langgraph.graph import START, END, StateGraph
 from langgraph.prebuilt import tools_condition, ToolNode
 
 from sentence_transformers import SentenceTransformer, CrossEncoder
 from langchain_huggingface import ChatHuggingFace, HuggingFaceEndpoint
 from langchain_core.messages import HumanMessage, SystemMessage
+from langchain_core.tools import tool
 from supabase.client import Client, create_client
 
 from utils import load_config, load_prompt, init_bm25_index, reciprocal_rank_fusion
@@ -79,19 +78,20 @@ _system_prompt = load_prompt("prompts/prompt.yaml")
 _thinking_enabled = config["models"]["llm"]["parameters"].get("thinking_enabled", True)
 
 
-class FinalAnswer(BaseModel):
-    """Strict GAIA-format answer extracted from the solver's reasoning."""
-    answer: str = Field(
-        description=(
-            "The raw answer value only. "
-            "Numbers: plain digits, no commas, no units, no symbols (write '1000000', not '1,000,000' or '$50'). "
-            "Strings: no articles ('a', 'an', 'the'), no markdown, no surrounding quotes, no trailing punctuation. "
-            "Lists: comma-separated with no extra spaces, in the order requested by the question."
-        )
-    )
+@tool
+def emit_final_answer(answer: str) -> str:
+    """Emit the final answer to the GAIA question in the strict scoring format.
+
+    Args:
+        answer: The raw answer value only.
+            Numbers: plain digits, no commas, no units, no symbols (write '1000000', not '1,000,000' or '$50').
+            Strings: no articles ('a', 'an', 'the'), no markdown, no surrounding quotes, no trailing punctuation.
+            Lists: comma-separated with no extra spaces, in the order requested by the question.
+    """
+    return answer
 
 
-formatter_llm = agent_llm.with_structured_output(FinalAnswer)
+formatter_llm = agent_llm.bind_tools([emit_final_answer], tool_choice="emit_final_answer")
 
 
 # ============================================
@@ -304,20 +304,27 @@ def formatter_node(state: AgentState) -> AgentState:
 
     prompt = [
         SystemMessage(content=(
-            "You extract the final answer from an agent's reasoning. "
-            "Apply the GAIA formatting rules exactly. "
-            "If the agent never produced an answer, return an empty string."
+            "You extract the final answer from an agent's reasoning and apply the GAIA "
+            "formatting rules exactly. You MUST call the `emit_final_answer` tool with "
+            "the extracted value. If the agent never produced an answer, call it with an "
+            "empty string."
         )),
         HumanMessage(content=(
             f"Question:\n{question}\n\n"
             f"Agent reasoning and conclusion:\n{solver_output}\n\n"
-            "Extract the final answer."
+            "Extract the final answer and call emit_final_answer."
         )),
     ]
 
     try:
         result = formatter_llm.invoke(prompt)
-        return {"final_answer": result.answer.strip()}
+        for tc in getattr(result, "tool_calls", None) or []:
+            if tc.get("name") == "emit_final_answer":
+                return {"final_answer": str(tc.get("args", {}).get("answer", "")).strip()}
+        # Model returned text instead of calling the tool — regex over its content.
+        content = result.content or ""
+        match = re.search(r'FINAL ANSWER:\s*(.*)', content, re.DOTALL | re.IGNORECASE)
+        return {"final_answer": (match.group(1).strip() if match else content.strip())}
     except Exception as e:
         print(f"Formatter error: {e}")
         match = re.search(r'FINAL ANSWER:\s*(.*)', solver_output, re.DOTALL | re.IGNORECASE)

config.yaml

@@ -37,8 +37,6 @@ models:
       
 graph:
   recursion_limit: 20                     # Max steps before the graph terminates
-  thread_id: "default-user"               # Default session identifier
-  memory_type: "sqlite"                   # Persistence method for checkpointers
 
 api:
   base_url: "https://agents-course-unit4-scoring.hf.space"

tools.py

@@ -135,13 +135,13 @@ def fetch_webpage(url: str) -> str:
     try:
         downloaded = trafilatura.fetch_url(url)
         if downloaded is None:
-            return f"Error: Could not fetch {url}"
+            return f"[fetch_webpage] could not fetch {url}"
         text = trafilatura.extract(downloaded, include_tables=True, include_links=False)
         if text is None:
-            return f"Error: Could not extract content from {url}"
+            return f"[fetch_webpage] could not extract content from {url}"
         return f"Page content from {url}:\n\n{text}"
     except Exception as e:
-        return f"Error fetching webpage: {e}"
+        return f"[fetch_webpage] failed: {e}"
 
 
 @tool
@@ -169,11 +169,11 @@ def python_eval(code: str) -> str:
         os.unlink(tmp_path)
         if result.returncode == 0:
             return f"Output:\n{result.stdout}"
-        return f"Error (exit {result.returncode}):\n{result.stderr}"
+        return f"[python_eval] exit {result.returncode}:\n{result.stderr}"
     except subprocess.TimeoutExpired:
-        return "Error: execution timed out (30s limit)"
+        return "[python_eval] execution timed out (30s limit)"
     except Exception as e:
-        return f"Error: {e}"
+        return f"[python_eval] failed: {e}"
 
 
 # ============================================
@@ -194,7 +194,7 @@ def analyze_image(image_path: str, question: str) -> str:
     """
     try:
         if not os.path.exists(image_path):
-            return f"Error: Image file not found at {image_path}"
+            return f"[analyze_image] image file not found at {image_path}"
 
         with open(image_path, "rb") as img_file:
             image_data = base64.b64encode(img_file.read()).decode("utf-8")
@@ -221,7 +221,7 @@ def analyze_image(image_path: str, question: str) -> str:
         return output.choices[0].message.content
 
     except Exception as e:
-        return f"Error analyzing image with VLM: {str(e)}"
+        return f"[analyze_image] VLM call failed: {e}"
 
 
 # ============================================
@@ -251,7 +251,7 @@ def read_pdf(file_path: str) -> str:
         
         return "\n\n".join(text) if text else "[Empty PDF]"
     except Exception as e:
-        return f"Error reading PDF: {e}"
+        return f"[read_pdf] failed to read PDF: {e}"
 
 
 @tool
@@ -283,7 +283,7 @@ def read_docx(file_path: str) -> str:
 
         return "\n\n".join(text_parts) if text_parts else "[Empty document]"
     except Exception as e:
-        return f"Error reading DOCX: {e}"
+        return f"[read_docx] failed to read DOCX: {e}"
 
 
 @tool
@@ -313,7 +313,7 @@ def read_pptx(file_path: str) -> str:
         
         return "\n\n".join(text) if text else "[Empty presentation]"
     except Exception as e:
-        return f"Error reading PPTX: {e}"
+        return f"[read_pptx] failed to read PPTX: {e}"
 
 
 @tool
@@ -331,7 +331,7 @@ def read_text_file(file_path: str) -> str:
         with open(file_path, 'r', encoding='utf-8', errors='replace') as f:
             return f.read()
     except Exception as e:
-        return f"Error reading text file: {e}"
+        return f"[read_text_file] failed: {e}"
 
 
 # ============================================
@@ -362,7 +362,7 @@ def read_csv(file_path: str) -> str:
             output += f"\n\nComplete data:\n{df}"
         return output
     except Exception as e:
-        return f"Error reading CSV: {e}"
+        return f"[read_csv] failed to read CSV: {e}"
 
 
 @tool
@@ -400,7 +400,7 @@ def read_excel(file_path: str, sheet_id: int = 0) -> str:
             output += f"\n\nComplete data:\n{df}"
         return output
     except Exception as e:
-        return f"Error reading Excel: {e}"
+        return f"[read_excel] failed to read Excel: {e}"
 
 
 @tool
@@ -419,7 +419,7 @@ def read_jsonld(file_path: str) -> str:
             data = json.load(f)
         return f"JSON-LD Content:\n{json.dumps(data, indent=2)}"
     except Exception as e:
-        return f"Error reading JSON-LD: {e}"
+        return f"[read_jsonld] failed to read JSON-LD: {e}"
 
 
 @tool
@@ -465,7 +465,7 @@ def read_pdb(file_path: str) -> str:
         
         return "\n".join(info)
     except Exception as e:
-        return f"Error reading PDB: {e}"
+        return f"[read_pdb] failed to read PDB: {e}"
 
 
 # ============================================
@@ -487,7 +487,7 @@ def transcribe_audio(file_path: str) -> str:
         result = _hf_client.automatic_speech_recognition(audio=file_path, model=_asr_model_name)
         return f"Audio Transcription:\n{result.text}"
     except Exception as e:
-        return f"Error transcribing audio: {e}"
+        return f"[transcribe_audio] failed: {e}"
 
 
 # ============================================
@@ -510,7 +510,7 @@ def read_python_file(file_path: str) -> str:
             code = f.read()
         return f"Python Code:\n```python\n{code}\n```"
     except Exception as e:
-        return f"Error reading Python file: {e}"
+        return f"[read_python_file] failed: {e}"
 
 
 # ============================================
@@ -550,7 +550,7 @@ def extract_zip(file_path: str) -> str:
         
         return "\n".join(results)
     except Exception as e:
-        return f"Error extracting ZIP: {e}"
+        return f"[extract_zip] failed: {e}"
 
 
 # ============================================