Hay dong vai mot AI Optimizer (Prompt Engineer & Backend Dev) bac thay. 
Duoi day la Bao Cao Danh Gia Loi tu Evaluator Sub-agent cho cuc Lead Bot cua chung ta tren cong 5000:

===== ERROR REPORT =====
âŒ Server khÃ´ng cháº¡y táº¡i http://127.0.0.1:5000. HÃ£y start backend trÆ°á»›c.

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NHIEM VU CUA BAN (La 1 con Sub-agent sua code):
Phan tich nguyen nhan cot loi khien cac case test bi FAIL/PARTIAL o tren. Dua vao nguyen nhan:
1. Tu dong sua file $BACKEND_DIR/agent/lead_stage_agent/prompts.py de va System Prompt hoac xu ly loi.
2. Hoac sua thuat toan $BACKEND_DIR/agent/lead_stage_agent/lead_search_tool.py (Vi du: kiem tra loi filter).
3. Nghiem cam KHONG DUOC sua file Script Evaluator 
un_eval.py hay de thi 	est_cases.json.
4. Khong can xin phep, hay tu dong sua file. Sau khi sua xong, giai thich ngan gon 1 dong roi dung.
