diff --git a/researchers/web/agent.py b/researchers/web/agent.py
index e2944fc..391e106 100644
--- a/researchers/web/agent.py
+++ b/researchers/web/agent.py
@@ -448,7 +448,7 @@ class WebResearcher:
 
         response = self.client.messages.create(
             model=self.model_id,
-            max_tokens=4096,
+            max_tokens=16384,
             messages=[{"role": "user", "content": prompt}],
         )
 
@@ -457,6 +457,7 @@ class WebResearcher:
 
         # Parse the JSON response
         raw_text = response.content[0].text.strip()
+        stop_reason = response.stop_reason
         # Strip markdown fences if the model added them despite instructions
         if raw_text.startswith("```"):
             raw_text = raw_text.split("\n", 1)[1] if "\n" in raw_text else raw_text[3:]
@@ -465,11 +466,16 @@ class WebResearcher:
 
         try:
             data = json.loads(raw_text)
-        except json.JSONDecodeError:
+        except json.JSONDecodeError as parse_err:
             trace.log_step(
                 "synthesis_error",
-                decision="Failed to parse synthesis JSON, returning fallback",
-                raw_response=raw_text[:1000],
+                decision=(
+                    f"Failed to parse synthesis JSON ({parse_err}); "
+                    f"stop_reason={stop_reason}"
+                ),
+                stop_reason=stop_reason,
+                parse_error=str(parse_err),
+                raw_response=raw_text,
             )
             return self._fallback_result(
                 question, evidence, trace, total_tokens, iterations,