fix(backend): default max_tokens for Anthropic model validation (#1549)

Co-authored-by: Cursor Agent <cursoragent@cursor.com>
Co-authored-by: emag165 <emag165@users.noreply.github.com>
Co-authored-by: Sun Tao <2605127667@qq.com>

Author: 3 people

backend/app/agent/agent_model.py

@@ -136,11 +136,11 @@ def agent_model(
             )
             model_platform_enum = None
 
-    if (
-        effective_config["model_platform"].lower() == "anthropic"
-        and model_config.get("cache_control") is None
-    ):
-        model_config["cache_control"] = "5m"
+    if effective_config["model_platform"].lower() == "anthropic":
+        if model_config.get("cache_control") is None:
+            model_config["cache_control"] = "5m"
+        if model_config.get("max_tokens") is None:
+            model_config["max_tokens"] = 64000
 
     model = ModelFactory.create(
         model_platform=effective_config["model_platform"],

backend/app/component/model_validation.py

@@ -227,6 +227,10 @@ def create_agent(
         raise ValueError(f"Invalid model_type: {model_type}")
     if platform is None:
         raise ValueError(f"Invalid model_platform: {model_platform}")
+    if str(platform).lower() == "anthropic":
+        model_config_dict = dict(model_config_dict or {})
+        if model_config_dict.get("max_tokens") is None:
+            model_config_dict["max_tokens"] = 4096
     model = ModelFactory.create(
         model_platform=platform,
         model_type=mtype,
@@ -326,6 +330,10 @@ def validate_model_with_details(
             "Creating model",
             extra={"platform": model_platform, "model_type": model_type},
         )
+        if str(model_platform).lower() == "anthropic":
+            model_config_dict = dict(model_config_dict or {})
+            if model_config_dict.get("max_tokens") is None:
+                model_config_dict["max_tokens"] = 4096
         model = ModelFactory.create(
             model_platform=model_platform,
             model_type=model_type,