diff --git a/graphiti_core/prompts/dedupe_edges.py b/graphiti_core/prompts/dedupe_edges.py
index bfc46a6fb..36f5f7a46 100644
--- a/graphiti_core/prompts/dedupe_edges.py
+++ b/graphiti_core/prompts/dedupe_edges.py
@@ -23,11 +23,11 @@
 
 class EdgeDuplicate(BaseModel):
     duplicate_facts: list[int] = Field(
-        ...,
+        default_factory=list,
         description='List of idx values of duplicate facts (only from EXISTING FACTS range). Empty list if none.',
     )
     contradicted_facts: list[int] = Field(
-        ...,
+        default_factory=list,
         description='List of idx values of contradicted facts (from full idx range). Empty list if none.',
     )
 
diff --git a/graphiti_core/prompts/dedupe_nodes.py b/graphiti_core/prompts/dedupe_nodes.py
index 1cdcb1b6f..6be312159 100644
--- a/graphiti_core/prompts/dedupe_nodes.py
+++ b/graphiti_core/prompts/dedupe_nodes.py
@@ -35,7 +35,9 @@ class NodeDuplicate(BaseModel):
 
 
 class NodeResolutions(BaseModel):
-    entity_resolutions: list[NodeDuplicate] = Field(..., description='List of resolved nodes')
+    entity_resolutions: list[NodeDuplicate] = Field(
+        default_factory=list, description='List of resolved nodes'
+    )
 
 
 class Prompt(Protocol):
diff --git a/graphiti_core/prompts/extract_edges.py b/graphiti_core/prompts/extract_edges.py
index 59d50a2c3..ca079daa1 100644
--- a/graphiti_core/prompts/extract_edges.py
+++ b/graphiti_core/prompts/extract_edges.py
@@ -48,7 +48,7 @@ class Edge(BaseModel):
 
 
 class ExtractedEdges(BaseModel):
-    edges: list[Edge]
+    edges: list[Edge] = Field(default_factory=list)
 
 
 class Prompt(Protocol):
diff --git a/graphiti_core/prompts/extract_nodes.py b/graphiti_core/prompts/extract_nodes.py
index e7e7bb995..48f241a46 100644
--- a/graphiti_core/prompts/extract_nodes.py
+++ b/graphiti_core/prompts/extract_nodes.py
@@ -34,7 +34,9 @@ class ExtractedEntity(BaseModel):
 
 
 class ExtractedEntities(BaseModel):
-    extracted_entities: list[ExtractedEntity] = Field(..., description='List of extracted entities')
+    extracted_entities: list[ExtractedEntity] = Field(
+        default_factory=list, description='List of extracted entities'
+    )
 
 
 class EntitySummary(BaseModel):
@@ -48,7 +50,7 @@ class SummarizedEntity(BaseModel):
 
 class SummarizedEntities(BaseModel):
     summaries: list[SummarizedEntity] = Field(
-        ...,
+        default_factory=list,
         description='List of entity summaries. Only include entities that need summary updates.',
     )
 
diff --git a/tests/prompts/__init__.py b/tests/prompts/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/tests/prompts/test_response_models.py b/tests/prompts/test_response_models.py
new file mode 100644
index 000000000..45aa97583
--- /dev/null
+++ b/tests/prompts/test_response_models.py
@@ -0,0 +1,100 @@
+"""Regression tests for response model defaults.
+
+When LLM providers (Anthropic, Gemini) return empty tool input ``{}``,
+response models with required list fields crash with ``ValidationError``.
+These tests verify that all list-based response models accept empty input
+and produce valid instances with empty lists.
+"""
+
+from graphiti_core.prompts.dedupe_edges import EdgeDuplicate
+from graphiti_core.prompts.dedupe_nodes import NodeDuplicate, NodeResolutions
+from graphiti_core.prompts.extract_edges import Edge, ExtractedEdges
+from graphiti_core.prompts.extract_nodes import (
+    ExtractedEntities,
+    ExtractedEntity,
+    SummarizedEntities,
+    SummarizedEntity,
+)
+
+
+class TestResponseModelsAcceptEmptyInput:
+    """Verify that response models handle empty LLM output without crashing.
+
+    This simulates the exact code path in anthropic_client.py (line 403):
+        model_instance = response_model(**response)
+    where response is {} (empty dict from tool_use input).
+    """
+
+    def test_extracted_entities_empty_input(self):
+        result = ExtractedEntities(**{})
+        assert result.extracted_entities == []
+
+    def test_extracted_edges_empty_input(self):
+        result = ExtractedEdges(**{})
+        assert result.edges == []
+
+    def test_edge_duplicate_empty_input(self):
+        result = EdgeDuplicate(**{})
+        assert result.duplicate_facts == []
+        assert result.contradicted_facts == []
+
+    def test_node_resolutions_empty_input(self):
+        result = NodeResolutions(**{})
+        assert result.entity_resolutions == []
+
+    def test_summarized_entities_empty_input(self):
+        result = SummarizedEntities(**{})
+        assert result.summaries == []
+
+
+class TestResponseModelsPopulatedInput:
+    """Verify that response models still work correctly with populated input."""
+
+    def test_extracted_entities_with_data(self):
+        result = ExtractedEntities(
+            extracted_entities=[
+                ExtractedEntity(name='Alice', entity_type_id=1),
+                ExtractedEntity(name='Bob', entity_type_id=2),
+            ]
+        )
+        assert len(result.extracted_entities) == 2
+        assert result.extracted_entities[0].name == 'Alice'
+
+    def test_extracted_edges_with_data(self):
+        result = ExtractedEdges(
+            edges=[
+                Edge(
+                    source_entity_name='Alice',
+                    target_entity_name='Bob',
+                    relation_type='KNOWS',
+                    fact='Alice knows Bob',
+                    valid_at=None,
+                    invalid_at=None,
+                )
+            ]
+        )
+        assert len(result.edges) == 1
+        assert result.edges[0].relation_type == 'KNOWS'
+
+    def test_edge_duplicate_with_data(self):
+        result = EdgeDuplicate(duplicate_facts=[1, 2], contradicted_facts=[3])
+        assert result.duplicate_facts == [1, 2]
+        assert result.contradicted_facts == [3]
+
+    def test_node_resolutions_with_data(self):
+        result = NodeResolutions(
+            entity_resolutions=[
+                NodeDuplicate(id=1, name='Alice', duplicate_candidate_id=-1),
+            ]
+        )
+        assert len(result.entity_resolutions) == 1
+        assert result.entity_resolutions[0].duplicate_candidate_id == -1
+
+    def test_summarized_entities_with_data(self):
+        result = SummarizedEntities(
+            summaries=[
+                SummarizedEntity(name='Alice', summary='A person named Alice'),
+            ]
+        )
+        assert len(result.summaries) == 1
+        assert result.summaries[0].name == 'Alice'