diff --git a/anthropic/anthropic.go b/anthropic/anthropic.go
index f4d9a6e23..9cb2c75c4 100644
--- a/anthropic/anthropic.go
+++ b/anthropic/anthropic.go
@@ -377,7 +377,7 @@ func convertMessage(msg MessageParam) ([]api.Message, error) {
 					},
 				}
 				if input, ok := blockMap["input"].(map[string]any); ok {
-					tc.Function.Arguments = api.ToolCallFunctionArguments(input)
+					tc.Function.Arguments = mapToArgs(input)
 				}
 				toolCalls = append(toolCalls, tc)
 
@@ -767,3 +767,12 @@ func GenerateMessageID() string {
 func ptr(s string) *string {
 	return &s
 }
+
+// mapToArgs converts a map to ToolCallFunctionArguments
+func mapToArgs(m map[string]any) api.ToolCallFunctionArguments {
+	args := api.NewToolCallFunctionArguments()
+	for k, v := range m {
+		args.Set(k, v)
+	}
+	return args
+}
diff --git a/anthropic/anthropic_test.go b/anthropic/anthropic_test.go
index 8228bd37b..117d183c9 100644
--- a/anthropic/anthropic_test.go
+++ b/anthropic/anthropic_test.go
@@ -14,6 +14,15 @@ const (
 	testImage = `iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAQAAAC1HAwCAAAAC0lEQVR42mNk+A8AAQUBAScY42YAAAAASUVORK5CYII=`
 )
 
+// testArgs creates ToolCallFunctionArguments from a map (convenience function for tests)
+func testArgs(m map[string]any) api.ToolCallFunctionArguments {
+	args := api.NewToolCallFunctionArguments()
+	for k, v := range m {
+		args.Set(k, v)
+	}
+	return args
+}
+
 func TestFromMessagesRequest_Basic(t *testing.T) {
 	req := MessagesRequest{
 		Model:     "test-model",
@@ -468,7 +477,7 @@ func TestToMessagesResponse_WithToolCalls(t *testing.T) {
 					ID: "call_123",
 					Function: api.ToolCallFunction{
 						Name:      "get_weather",
-						Arguments: map[string]any{"location": "Paris"},
+						Arguments: testArgs(map[string]any{"location": "Paris"}),
 					},
 				},
 			},
@@ -662,7 +671,7 @@ func TestStreamConverter_WithToolCalls(t *testing.T) {
 					ID: "call_123",
 					Function: api.ToolCallFunction{
 						Name:      "get_weather",
-						Arguments: map[string]any{"location": "Paris"},
+						Arguments: testArgs(map[string]any{"location": "Paris"}),
 					},
 				},
 			},
@@ -708,6 +717,8 @@ func TestStreamConverter_ToolCallWithUnmarshalableArgs(t *testing.T) {
 
 	// Create a channel which cannot be JSON marshaled
 	unmarshalable := make(chan int)
+	badArgs := api.NewToolCallFunctionArguments()
+	badArgs.Set("channel", unmarshalable)
 
 	resp := api.ChatResponse{
 		Model: "test-model",
@@ -718,7 +729,7 @@ func TestStreamConverter_ToolCallWithUnmarshalableArgs(t *testing.T) {
 					ID: "call_bad",
 					Function: api.ToolCallFunction{
 						Name:      "bad_function",
-						Arguments: map[string]any{"channel": unmarshalable},
+						Arguments: badArgs,
 					},
 				},
 			},
@@ -752,6 +763,8 @@ func TestStreamConverter_MultipleToolCallsWithMixedValidity(t *testing.T) {
 	conv := NewStreamConverter("msg_123", "test-model")
 
 	unmarshalable := make(chan int)
+	badArgs := api.NewToolCallFunctionArguments()
+	badArgs.Set("channel", unmarshalable)
 
 	resp := api.ChatResponse{
 		Model: "test-model",
@@ -762,14 +775,14 @@ func TestStreamConverter_MultipleToolCallsWithMixedValidity(t *testing.T) {
 					ID: "call_good",
 					Function: api.ToolCallFunction{
 						Name:      "good_function",
-						Arguments: map[string]any{"location": "Paris"},
+						Arguments: testArgs(map[string]any{"location": "Paris"}),
 					},
 				},
 				{
 					ID: "call_bad",
 					Function: api.ToolCallFunction{
 						Name:      "bad_function",
-						Arguments: map[string]any{"channel": unmarshalable},
+						Arguments: badArgs,
 					},
 				},
 			},
diff --git a/middleware/anthropic_test.go b/middleware/anthropic_test.go
index b444e83ab..40df7fbb4 100644
--- a/middleware/anthropic_test.go
+++ b/middleware/anthropic_test.go
@@ -11,6 +11,7 @@ import (
 
 	"github.com/gin-gonic/gin"
 	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
 
 	"github.com/ollama/ollama/anthropic"
 	"github.com/ollama/ollama/api"
@@ -25,6 +26,15 @@ func captureAnthropicRequest(capturedRequest any) gin.HandlerFunc {
 	}
 }
 
+// testProps creates ToolPropertiesMap from a map (convenience function for tests)
+func testProps(m map[string]api.ToolProperty) *api.ToolPropertiesMap {
+	props := api.NewToolPropertiesMap()
+	for k, v := range m {
+		props.Set(k, v)
+	}
+	return props
+}
+
 func TestAnthropicMessagesMiddleware(t *testing.T) {
 	type testCase struct {
 		name string
@@ -156,9 +166,9 @@ func TestAnthropicMessagesMiddleware(t *testing.T) {
 							Parameters: api.ToolFunctionParameters{
 								Type:     "object",
 								Required: []string{"location"},
-								Properties: map[string]api.ToolProperty{
+								Properties: testProps(map[string]api.ToolProperty{
 									"location": {Type: api.PropertyType{"string"}},
-								},
+								}),
 							},
 						},
 					},
@@ -193,7 +203,7 @@ func TestAnthropicMessagesMiddleware(t *testing.T) {
 								ID: "call_123",
 								Function: api.ToolCallFunction{
 									Name:      "get_weather",
-									Arguments: api.ToolCallFunctionArguments{"location": "Paris"},
+									Arguments: testArgs(map[string]any{"location": "Paris"}),
 								},
 							},
 						},
@@ -344,7 +354,8 @@ func TestAnthropicMessagesMiddleware(t *testing.T) {
 				t.Errorf("model mismatch: got %q, want %q", capturedRequest.Model, tc.req.Model)
 			}
 
-			if diff := cmp.Diff(tc.req.Messages, capturedRequest.Messages); diff != "" {
+			if diff := cmp.Diff(tc.req.Messages, capturedRequest.Messages,
+				cmpopts.IgnoreUnexported(api.ToolCallFunctionArguments{}, api.ToolPropertiesMap{})); diff != "" {
 				t.Errorf("messages mismatch (-want +got):\n%s", diff)
 			}
 
@@ -492,11 +503,11 @@ func TestAnthropicWriter_ErrorFromRoutes(t *testing.T) {
 	gin.SetMode(gin.TestMode)
 
 	tests := []struct {
-		name           string
-		statusCode     int
-		errorPayload   any
-		wantErrorType  string
-		wantMessage    string
+		name          string
+		statusCode    int
+		errorPayload  any
+		wantErrorType string
+		wantMessage   string
 	}{
 		// routes.go sends errors without StatusCode in JSON, so we must use HTTP status
 		{