fix: update descriptions with removed constraint info in filter_anthropic_output_schema

Address review feedback: the function now appends removed constraint
information to the description field (matching Anthropic SDK behavior),
rather than silently dropping constraints.

litellm/llms/anthropic/chat/transformation.py

@@ -240,10 +240,41 @@ class AnthropicConfig(AnthropicModelInfo, BaseConfig):
             "minLength", "maxLength",         # string constraints
         }
 
+        # Build description additions from removed constraints
+        constraint_descriptions: list = []
+        constraint_labels = {
+            "minItems": "minimum number of items: {}",
+            "maxItems": "maximum number of items: {}",
+            "minimum": "minimum value: {}",
+            "maximum": "maximum value: {}",
+            "exclusiveMinimum": "exclusive minimum value: {}",
+            "exclusiveMaximum": "exclusive maximum value: {}",
+            "minLength": "minimum length: {}",
+            "maxLength": "maximum length: {}",
+        }
+        for field in unsupported_fields:
+            if field in schema:
+                constraint_descriptions.append(
+                    constraint_labels[field].format(schema[field])
+                )
+
         result: Dict[str, Any] = {}
+
+        # Update description with removed constraint info
+        if constraint_descriptions:
+            existing_desc = schema.get("description", "")
+            constraint_note = "Note: " + ", ".join(constraint_descriptions) + "."
+            if existing_desc:
+                result["description"] = existing_desc + " " + constraint_note
+            else:
+                result["description"] = constraint_note
+
         for key, value in schema.items():
             if key in unsupported_fields:
                 continue
+            if key == "description" and "description" in result:
+                # Already handled above
+                continue
 
             if key == "properties" and isinstance(value, dict):
                 result[key] = {

tests/litellm/llms/anthropic/test_anthropic_schema_filter.py

@@ -40,7 +40,13 @@ class TestFilterAnthropicOutputSchema:
         
         # Other fields preserved
         assert result["properties"]["age"]["type"] == "integer"
-        assert result["properties"]["age"]["description"] == "Person's age"
+        # Description should be updated with removed constraint info
+        assert "Person's age" in result["properties"]["age"]["description"]
+        assert "minimum value: 0" in result["properties"]["age"]["description"]
+        assert "maximum value: 150" in result["properties"]["age"]["description"]
+        # Score had no description, should get one from constraints
+        assert "exclusive minimum value: 0" in result["properties"]["score"]["description"]
+        assert "exclusive maximum value: 100" in result["properties"]["score"]["description"]
 
     def test_removes_string_constraints(self):
         """Test that minLength/maxLength are removed from string schemas."""
@@ -60,6 +66,9 @@ class TestFilterAnthropicOutputSchema:
         assert "minLength" not in result["properties"]["name"]
         assert "maxLength" not in result["properties"]["name"]
         assert result["properties"]["name"]["type"] == "string"
+        # Description should contain constraint info
+        assert "minimum length: 1" in result["properties"]["name"]["description"]
+        assert "maximum length: 100" in result["properties"]["name"]["description"]
 
     def test_removes_array_constraints(self):
         """Test that minItems/maxItems are removed from array schemas."""
@@ -76,6 +85,9 @@ class TestFilterAnthropicOutputSchema:
         assert "maxItems" not in result
         assert result["type"] == "array"
         assert result["items"] == {"type": "string"}
+        # Description should contain constraint info
+        assert "minimum number of items: 1" in result["description"]
+        assert "maximum number of items: 10" in result["description"]
 
     def test_handles_nested_schemas(self):
         """Test that nested schemas are also filtered."""