diff --git a/api/types.go b/api/types.go
index 3ccf3ce2..d24178d1 100644
--- a/api/types.go
+++ b/api/types.go
@@ -341,7 +341,7 @@ type ToolFunctionParameters struct {
 	Defs       any                     `json:"$defs,omitempty"`
 	Items      any                     `json:"items,omitempty"`
 	Required   []string                `json:"required,omitempty"`
-	Properties map[string]ToolProperty `json:"properties"`
+	Properties map[string]ToolProperty `json:"properties,omitempty"`
 }
 
 func (t *ToolFunctionParameters) String() string {
@@ -352,7 +352,7 @@ func (t *ToolFunctionParameters) String() string {
 type ToolFunction struct {
 	Name        string                 `json:"name"`
 	Description string                 `json:"description,omitempty"`
-	Parameters  ToolFunctionParameters `json:"parameters"`
+	Parameters  ToolFunctionParameters `json:"parameters,omitempty"`
 }
 
 func (t *ToolFunction) String() string {
diff --git a/server/routes_debug_test.go b/server/routes_debug_test.go
index 6f9104c3..012125b5 100644
--- a/server/routes_debug_test.go
+++ b/server/routes_debug_test.go
@@ -363,7 +363,7 @@ func TestChatDebugRenderOnly(t *testing.T) {
 				DebugRenderOnly: true,
 			},
 			expectDebug:    true,
-			expectTemplate: "[{\"type\":\"function\",\"function\":{\"name\":\"get_weather\",\"description\":\"Get weather information\",\"parameters\":{\"type\":\"\",\"properties\":null}}}]user: Get the weather\n",
+			expectTemplate: "[{\"type\":\"function\",\"function\":{\"name\":\"get_weather\",\"description\":\"Get weather information\",\"parameters\":{\"type\":\"\"}}}]user: Get the weather\n",
 		},
 	}