diff --git a/src/webwright/models/anthropic_model.py b/src/webwright/models/anthropic_model.py
index 53393b5..cf54077 100644
--- a/src/webwright/models/anthropic_model.py
+++ b/src/webwright/models/anthropic_model.py
@@ -101,21 +101,33 @@ def _usage_from_anthropic_payload(payload: dict[str, Any]) -> dict[str, int]:
     input_tokens = _safe_int(usage.get("input_tokens"))
     output_tokens = _safe_int(usage.get("output_tokens"))
     cached_input_tokens = _safe_int(usage.get("cache_read_input_tokens"))
+    cache_creation_tokens = _safe_int(usage.get("cache_creation_input_tokens"))
     return {
         "input_tokens": input_tokens,
         "output_tokens": output_tokens,
         "total_tokens": input_tokens + output_tokens,
         "cached_input_tokens": cached_input_tokens,
+        "cache_creation_input_tokens": cache_creation_tokens,
         "reasoning_output_tokens": 0,
     }
 
 
 def _metrics_input_from_anthropic(
-    system_prompt: str | None, anthropic_messages: list[dict[str, Any]]
+    system_prompt: str | list[dict[str, Any]] | None,
+    anthropic_messages: list[dict[str, Any]],
 ) -> list[dict[str, Any]]:
     items: list[dict[str, Any]] = []
     if system_prompt:
-        items.append({"content": [{"type": "input_text", "text": system_prompt}]})
+        if isinstance(system_prompt, str):
+            items.append({"content": [{"type": "input_text", "text": system_prompt}]})
+        else:
+            parts = [
+                {"type": "input_text", "text": block.get("text", "")}
+                for block in system_prompt
+                if isinstance(block, dict) and block.get("type") == "text"
+            ]
+            if parts:
+                items.append({"content": parts})
     for msg in anthropic_messages:
         content = msg.get("content", "")
         if isinstance(content, str):
@@ -179,7 +191,13 @@ def _build_payload(self, messages: list[dict[str, Any]]) -> dict[str, Any]:
             "max_tokens": self.config.max_output_tokens,
         }
         if system_prompt:
-            payload["system"] = system_prompt
+            payload["system"] = [
+                {
+                    "type": "text",
+                    "text": system_prompt,
+                    "cache_control": {"type": "ephemeral"},
+                }
+            ]
         return payload
 
     def _request_metrics_input(self, payload: dict[str, Any]) -> list[dict[str, Any]]:
diff --git a/src/webwright/models/base.py b/src/webwright/models/base.py
index 7728bb8..ba4115e 100644
--- a/src/webwright/models/base.py
+++ b/src/webwright/models/base.py
@@ -197,6 +197,7 @@ def _request_metrics_from_serialized_input(serialized_input: list[dict[str, Any]
     "output_tokens",
     "total_tokens",
     "cached_input_tokens",
+    "cache_creation_input_tokens",
     "reasoning_output_tokens",
 )