diff --git a/src/mcprobe/judge/prompts.py b/src/mcprobe/judge/prompts.py
index bc4d58e..355bb4e 100644
--- a/src/mcprobe/judge/prompts.py
+++ b/src/mcprobe/judge/prompts.py
@@ -22,9 +22,16 @@
 {conversation_transcript}
 
 ## Your Task
-Evaluate whether the agent's responses so far have satisfied ALL the correctness criteria.
-Be strict: a criterion is only met if the agent has clearly and completely addressed it.
-Do not mark criteria as met if the information is partial, vague, or requires inference.
+Determine if the conversation should END because the user's question has been answered.
+
+CRITICAL - User satisfaction signals completion:
+- If the user says "thanks", "that's what I needed", "perfect", "great", etc. → ALL CRITERIA MET
+- User satisfaction is the PRIMARY signal - if the user is happy, mark all_criteria_met: true
+- Do NOT continue nitpicking criteria if the user has expressed satisfaction
+
+Secondary check (only if user hasn't expressed satisfaction):
+- Evaluate if the agent substantively addressed each criterion
+- Be reasonable - minor differences in wording or thresholds are OK
 
 IMPORTANT: For correctness_results, use the EXACT criterion text as the key.
 Do NOT paraphrase, shorten, or modify the criterion text in any way.
diff --git a/src/mcprobe/synthetic_user/prompts.py b/src/mcprobe/synthetic_user/prompts.py
index e2217d6..73bf2b2 100644
--- a/src/mcprobe/synthetic_user/prompts.py
+++ b/src/mcprobe/synthetic_user/prompts.py
@@ -28,6 +28,14 @@
 
 RESPONSE LENGTH: Keep responses to 1-2 SHORT sentences. If satisfied, just say thanks briefly.
 
+CRITICAL - STAY ON TOPIC:
+- ONLY ask about your ORIGINAL question - never invent new questions
+- Once your original question is answered, DO NOT extend the conversation
+- If the assistant says "let me know if you need anything else" and you're satisfied,
+  just say "That's all I needed, thanks" or similar - DO NOT ask new questions
+- NEVER ask follow-up questions about different topics, different data, or different analyses
+- Your ONLY goal is to get your initial question answered - nothing more
+
 ## The User's Persona
 {persona}
 
@@ -53,24 +61,26 @@
    - If the assistant keeps asking questions, the user may express mild impatience
 
 2. When the assistant provides an answer - BE A REAL USER:
-   - ALWAYS compare the response to your original question
-   - If it FULLY answers your question, thank them briefly
-   - If it's INCOMPLETE or OFF-TOPIC, be direct and persistent:
-     * Point out what's missing: "You mentioned X, but I asked about Y"
-     * Rephrase your question more directly: "To clarify, what I need is..."
-     * Don't just accept partial answers - push back politely but firmly
-   - If it's VAGUE, demand specifics: "Can you be more specific about..."
-   - Real users don't give up easily - they persist until they get what they need
-
-3. Persistence patterns (use these when unsatisfied):
-   - "That's helpful, but you didn't address [specific part of my question]"
-   - "I understand, but what I really need to know is..."
-   - "Thanks, but can you tell me specifically about [original ask]?"
-   - "I'm still not clear on [the thing you actually asked about]"
+   - ALWAYS compare the response to your ORIGINAL question (not any new topics)
+   - If it FULLY answers your original question, say "Thanks, that's what I needed"
+   - If it's INCOMPLETE for your ORIGINAL question, point out what's missing
+   - If it's VAGUE about your ORIGINAL question, ask for specifics
+   - NEVER invent new questions or ask about things outside your original query
+   - Once satisfied, END the conversation - do not extend it
+
+3. Persistence patterns (ONLY use when your ORIGINAL question is not fully answered):
+   - "That's helpful, but you didn't address [specific part of ORIGINAL question]"
+   - "Thanks, but I still need to know [something from ORIGINAL question]"
+   - Do NOT use these to ask NEW questions - only to clarify your ORIGINAL ask
 
 4. Keep responses SHORT (1-2 sentences max)
 
 5. The user is asking for help - do NOT provide information unprompted
+
+6. ENDING THE CONVERSATION:
+   - When your original question is answered, say "Thanks, that's what I needed" and STOP
+   - Do NOT ask "one more thing" or "also, can you tell me about..."
+   - Do NOT invent follow-up analyses or comparisons not in your original question
 """
 
 # Patience thresholds by level