tools - do not remove $defs

src/strands/tools/decorator.py

@@ -195,7 +195,7 @@ def _clean_pydantic_schema(self, schema: Dict[str, Any]) -> None:
             schema: The Pydantic-generated JSON schema to clean up (modified in place).
         """
         # Remove Pydantic metadata
-        keys_to_remove = ["title", "$defs", "additionalProperties"]
+        keys_to_remove = ["title", "additionalProperties"]
         for key in keys_to_remove:
             if key in schema:
                 del schema[key]

src/strands/tools/registry.py

@@ -538,6 +538,10 @@ def validate_tool_spec(self, tool_spec: ToolSpec) -> None:
                 }
                 continue
 
+            # It is expected that type and description are already included in referenced $def.
+            if "$ref" in prop_def:
+                continue
+
             if "type" not in prop_def:
                 prop_def["type"] = "string"
             if "description" not in prop_def:

src/strands/tools/tools.py

@@ -81,6 +81,11 @@ def _normalize_property(prop_name: str, prop_def: Any) -> Dict[str, Any]:
 
     # Copy existing property, ensuring defaults
     normalized_prop = prop_def.copy()
+
+    # It is expected that type and description are already included in referenced $def.
+    if "$ref" in normalized_prop:
+        return normalized_prop
+
     normalized_prop.setdefault("type", "string")
     normalized_prop.setdefault("description", f"Property {prop_name}")
     return normalized_prop