diff --git a/intercept_agent.py b/intercept_agent.py
index 381c82f..de6b7d3 100644
--- a/intercept_agent.py
+++ b/intercept_agent.py
@@ -3596,7 +3596,8 @@ class InterceptAgentHandler(BaseHTTPRequestHandler):
 
             if action == 'start':
                 result = mode_manager.start_mode(mode, body)
-                status = 200 if result.get('status') == 'started' else 400
+                # Accept both 'started' and 'success' as valid (quick scans return 'success')
+                status = 200 if result.get('status') in ('started', 'success') else 400
                 self._send_json(result, status)
             elif action == 'stop':
                 result = mode_manager.stop_mode(mode)
diff --git a/utils/agent_client.py b/utils/agent_client.py
index 47b3183..1192d39 100644
--- a/utils/agent_client.py
+++ b/utils/agent_client.py
@@ -83,10 +83,17 @@ class AgentClient:
         except requests.Timeout:
             raise AgentConnectionError(f"Request to agent timed out after {self.timeout}s")
         except requests.HTTPError as e:
-            raise AgentHTTPError(
-                f"Agent returned error: {e.response.status_code}",
-                status_code=e.response.status_code
-            )
+            # Try to extract error message from response body
+            error_msg = f"Agent returned error: {e.response.status_code}"
+            try:
+                error_data = e.response.json()
+                if 'message' in error_data:
+                    error_msg = error_data['message']
+                elif 'error' in error_data:
+                    error_msg = error_data['error']
+            except Exception:
+                pass
+            raise AgentHTTPError(error_msg, status_code=e.response.status_code)
         except requests.RequestException as e:
             raise AgentHTTPError(f"Request failed: {e}")
 
@@ -120,10 +127,17 @@ class AgentClient:
         except requests.Timeout:
             raise AgentConnectionError(f"Request to agent timed out after {self.timeout}s")
         except requests.HTTPError as e:
-            raise AgentHTTPError(
-                f"Agent returned error: {e.response.status_code}",
-                status_code=e.response.status_code
-            )
+            # Try to extract error message from response body
+            error_msg = f"Agent returned error: {e.response.status_code}"
+            try:
+                error_data = e.response.json()
+                if 'message' in error_data:
+                    error_msg = error_data['message']
+                elif 'error' in error_data:
+                    error_msg = error_data['error']
+            except Exception:
+                pass
+            raise AgentHTTPError(error_msg, status_code=e.response.status_code)
         except requests.RequestException as e:
             raise AgentHTTPError(f"Request failed: {e}")