diff --git a/.github/workflows/pr-test.yml b/.github/workflows/pr-test.yml
index 11efaf26..7e757265 100644
--- a/.github/workflows/pr-test.yml
+++ b/.github/workflows/pr-test.yml
@@ -41,6 +41,7 @@ env:
   OPENAI_TEST_KEY: ${{ secrets.OPENAI_TEST_KEY }}
   TEST_MOAPI_SECRET: ${{ secrets.OPENAI_TEST_KEY }}
   OPENAI_API_KEY: ${{ secrets.OPENAI_TEST_KEY }}
+  ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
   TEST_MOAPI_MIRROR: https://api.openai.com
 
   # DeepSeek API Configuration
diff --git a/.github/workflows/unit-test.yml b/.github/workflows/unit-test.yml
index 60f819ed..a9a3ceee 100644
--- a/.github/workflows/unit-test.yml
+++ b/.github/workflows/unit-test.yml
@@ -45,6 +45,7 @@ env:
   OPENAI_TEST_KEY: ${{ secrets.OPENAI_TEST_KEY }}
   TEST_MOAPI_SECRET: ${{ secrets.OPENAI_TEST_KEY }}
   OPENAI_API_KEY: ${{ secrets.OPENAI_TEST_KEY }}
+  ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
   TEST_MOAPI_MIRROR: https://api.openai.com
 
   # DeepSeek API Configuration
diff --git a/agent/llm/providers/anthropic/anthropic.go b/agent/llm/providers/anthropic/anthropic.go
index 4639bc22..a1843d5c 100644
--- a/agent/llm/providers/anthropic/anthropic.go
+++ b/agent/llm/providers/anthropic/anthropic.go
@@ -3,6 +3,7 @@ package anthropic
 import (
 	gocontext "context"
 	"fmt"
+	"sort"
 	"strings"
 	"time"
 
@@ -568,19 +569,26 @@ func (p *Provider) streamWithRetry(ctx *context.Context, messages []context.Mess
 	}
 
 	// Convert accumulated tool calls
+	// Note: tool call indices may not start at 0 (e.g. if text blocks precede tool_use blocks)
 	if len(accumulator.toolCalls) > 0 {
+		// Collect all indices and sort them to ensure deterministic order
+		indices := make([]int, 0, len(accumulator.toolCalls))
+		for idx := range accumulator.toolCalls {
+			indices = append(indices, idx)
+		}
+		sort.Ints(indices)
+
 		toolCalls := make([]context.ToolCall, 0, len(accumulator.toolCalls))
-		for i := 0; i < len(accumulator.toolCalls); i++ {
-			if tc, exists := accumulator.toolCalls[i]; exists {
-				toolCalls = append(toolCalls, context.ToolCall{
-					ID:   tc.id,
-					Type: "function",
-					Function: context.Function{
-						Name:      tc.name,
-						Arguments: tc.inputJSON,
-					},
-				})
-			}
+		for _, idx := range indices {
+			tc := accumulator.toolCalls[idx]
+			toolCalls = append(toolCalls, context.ToolCall{
+				ID:   tc.id,
+				Type: "function",
+				Function: context.Function{
+					Name:      tc.name,
+					Arguments: tc.inputJSON,
+				},
+			})
 		}
 		response.ToolCalls = toolCalls
 	}
diff --git a/agent/llm/providers/anthropic/anthropic_test.go b/agent/llm/providers/anthropic/anthropic_test.go
new file mode 100644
index 00000000..d1475f41
--- /dev/null
+++ b/agent/llm/providers/anthropic/anthropic_test.go
@@ -0,0 +1,301 @@
+package anthropic_test
+
+import (
+	gocontext "context"
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"github.com/yaoapp/gou/connector"
+	"github.com/yaoapp/gou/connector/openai"
+	"github.com/yaoapp/yao/agent/context"
+	"github.com/yaoapp/yao/agent/llm"
+	"github.com/yaoapp/yao/agent/output/message"
+	"github.com/yaoapp/yao/config"
+	"github.com/yaoapp/yao/openapi/oauth/types"
+	"github.com/yaoapp/yao/test"
+)
+
+// testConnectorID uses the cheapest model (Claude Haiku 3) to save tokens
+const testConnectorID = "claude.haiku-3_0"
+
+// TestAnthropicStreamBasic tests basic streaming completion with Anthropic API
+func TestAnthropicStreamBasic(t *testing.T) {
+	test.Prepare(t, config.Conf)
+	defer test.Clean()
+
+	conn, err := connector.Select(testConnectorID)
+	if err != nil {
+		t.Fatalf("Failed to select connector: %v", err)
+	}
+
+	// Verify it's an Anthropic connector
+	if !conn.Is(connector.ANTHROPIC) {
+		t.Fatal("Connector is not ANTHROPIC type")
+	}
+
+	// Use openai.Capabilities — SelectProvider auto-detects Anthropic format from connector type
+	options := &context.CompletionOptions{
+		Capabilities: &openai.Capabilities{
+			Streaming: true,
+			ToolCalls: true,
+		},
+	}
+
+	llmInstance, err := llm.New(conn, options)
+	if err != nil {
+		t.Fatalf("Failed to create LLM instance: %v", err)
+	}
+
+	messages := []context.Message{
+		{
+			Role:    context.RoleUser,
+			Content: "Say 'Hi' in one word.",
+		},
+	}
+
+	maxTokens := 10
+	options.MaxTokens = &maxTokens
+
+	ctx := newTestContext("test-anthropic-stream", testConnectorID)
+
+	var chunks []string
+	handler := func(chunkType message.StreamChunkType, data []byte) int {
+		chunks = append(chunks, string(data))
+		t.Logf("Stream chunk [%s]: %s", chunkType, string(data))
+		return 0
+	}
+
+	response, err := llmInstance.Stream(ctx, messages, options, handler)
+	if err != nil {
+		t.Fatalf("Stream failed: %v", err)
+	}
+
+	if response == nil {
+		t.Fatal("Response is nil")
+	}
+	if response.ID == "" {
+		t.Error("Response ID is empty")
+	}
+	if response.Model == "" {
+		t.Error("Response Model is empty")
+	}
+	if response.Content == "" {
+		t.Error("Response content is empty")
+	}
+	if response.FinishReason == "" {
+		t.Error("FinishReason is empty")
+	}
+	if response.Usage == nil {
+		t.Error("Response Usage is nil")
+	} else {
+		t.Logf("Usage: prompt=%d, completion=%d, total=%d",
+			response.Usage.PromptTokens, response.Usage.CompletionTokens, response.Usage.TotalTokens)
+	}
+	if len(chunks) == 0 {
+		t.Error("No streaming chunks received")
+	}
+
+	t.Logf("Final response content: %s", response.Content)
+	t.Logf("Total chunks received: %d", len(chunks))
+}
+
+// TestAnthropicStreamWithToolCalls tests streaming with tool calls via Anthropic API
+func TestAnthropicStreamWithToolCalls(t *testing.T) {
+	test.Prepare(t, config.Conf)
+	defer test.Clean()
+
+	conn, err := connector.Select(testConnectorID)
+	if err != nil {
+		t.Fatalf("Failed to select connector: %v", err)
+	}
+
+	options := &context.CompletionOptions{
+		Capabilities: &openai.Capabilities{
+			Streaming: true,
+			ToolCalls: true,
+		},
+	}
+
+	weatherTool := map[string]interface{}{
+		"type": "function",
+		"function": map[string]interface{}{
+			"name":        "get_weather",
+			"description": "Get the current weather for a location",
+			"parameters": map[string]interface{}{
+				"type": "object",
+				"properties": map[string]interface{}{
+					"location": map[string]interface{}{
+						"type":        "string",
+						"description": "The city name, e.g. Tokyo",
+					},
+				},
+				"required": []string{"location"},
+			},
+		},
+	}
+
+	options.Tools = []map[string]interface{}{weatherTool}
+	options.ToolChoice = "auto"
+
+	llmInstance, err := llm.New(conn, options)
+	if err != nil {
+		t.Fatalf("Failed to create LLM instance: %v", err)
+	}
+
+	messages := []context.Message{
+		{
+			Role:    context.RoleUser,
+			Content: "What's the weather in Tokyo?",
+		},
+	}
+
+	ctx := newTestContext("test-anthropic-tool", testConnectorID)
+
+	var toolCallChunks int
+	handler := func(chunkType message.StreamChunkType, data []byte) int {
+		if chunkType == message.ChunkToolCall {
+			toolCallChunks++
+		}
+		t.Logf("Stream chunk [%s]: %s", chunkType, string(data))
+		return 0
+	}
+
+	response, err := llmInstance.Stream(ctx, messages, options, handler)
+	if err != nil {
+		t.Fatalf("Stream with tool calls failed: %v", err)
+	}
+
+	if response == nil {
+		t.Fatal("Response is nil")
+	}
+
+	if len(response.ToolCalls) == 0 {
+		t.Error("Expected tool calls but got none")
+	} else {
+		t.Logf("Received %d tool call(s)", len(response.ToolCalls))
+		for i, tc := range response.ToolCalls {
+			t.Logf("Tool call %d: %s(%s)", i, tc.Function.Name, tc.Function.Arguments)
+
+			if tc.ID == "" {
+				t.Errorf("Tool call %d missing ID", i)
+			}
+			if tc.Function.Name == "" {
+				t.Errorf("Tool call %d missing function name", i)
+			}
+			if tc.Function.Name != "get_weather" {
+				t.Errorf("Tool call %d expected 'get_weather', got '%s'", i, tc.Function.Name)
+			}
+			if tc.Function.Arguments == "" {
+				t.Errorf("Tool call %d missing arguments", i)
+			}
+
+			// Verify arguments contain location
+			var args map[string]interface{}
+			if err := json.Unmarshal([]byte(tc.Function.Arguments), &args); err == nil {
+				if _, hasLocation := args["location"]; !hasLocation {
+					t.Errorf("Tool call %d arguments missing 'location'", i)
+				}
+			}
+		}
+	}
+
+	if response.FinishReason != context.FinishReasonToolCalls {
+		t.Logf("Warning: Expected finish_reason='tool_calls', got '%s'", response.FinishReason)
+	}
+
+	t.Logf("Final response: %+v", response)
+}
+
+// TestAnthropicStreamRetry tests error handling with invalid API key
+func TestAnthropicStreamRetry(t *testing.T) {
+	test.Prepare(t, config.Conf)
+	defer test.Clean()
+
+	connDSL := `{
+		"type": "anthropic",
+		"options": {
+			"model": "claude-3-haiku-20240307",
+			"key": "sk-ant-invalid-key-should-fail"
+		}
+	}`
+
+	conn, err := connector.New("anthropic", "test-anthropic-retry", []byte(connDSL))
+	if err != nil {
+		t.Fatalf("Failed to create test connector: %v", err)
+	}
+
+	options := &context.CompletionOptions{
+		Capabilities: &openai.Capabilities{
+			Streaming: true,
+			ToolCalls: true,
+		},
+	}
+
+	llmInstance, err := llm.New(conn, options)
+	if err != nil {
+		t.Fatalf("Failed to create LLM instance: %v", err)
+	}
+
+	messages := []context.Message{
+		{
+			Role:    context.RoleUser,
+			Content: "Test",
+		},
+	}
+
+	ctx := newTestContext("test-anthropic-retry", "test-anthropic-retry")
+
+	_, err = llmInstance.Stream(ctx, messages, options, nil)
+	if err == nil {
+		t.Fatal("Expected error due to invalid API key, but got success")
+	}
+
+	errMsg := strings.ToLower(err.Error())
+	hasExpectedError := strings.Contains(errMsg, "401") ||
+		strings.Contains(errMsg, "authentication") ||
+		strings.Contains(errMsg, "invalid") ||
+		strings.Contains(errMsg, "no data received")
+
+	if !hasExpectedError {
+		t.Errorf("Expected authentication error, got: %v", err)
+	}
+
+	t.Logf("Failed as expected with error: %v", err)
+}
+
+// ============================================================================
+// Helper Functions
+// ============================================================================
+
+func newTestContext(chatID, connectorID string) *context.Context {
+	authorized := &types.AuthorizedInfo{
+		Subject:   "test-user",
+		ClientID:  "test-client",
+		UserID:    "test-user-123",
+		TeamID:    "test-team-456",
+		TenantID:  "test-tenant-789",
+		SessionID: "test-session-id",
+		Constraints: types.DataConstraints{
+			TeamOnly: true,
+			Extra: map[string]interface{}{
+				"test": "anthropic-provider",
+			},
+		},
+	}
+
+	ctx := context.New(gocontext.Background(), authorized, chatID)
+	ctx.AssistantID = "test-assistant"
+	ctx.Locale = "en-us"
+	ctx.Theme = "light"
+	ctx.Client = context.Client{
+		Type:      "web",
+		UserAgent: "AnthropicProviderTest/1.0",
+		IP:        "127.0.0.1",
+	}
+	ctx.Referer = context.RefererAPI
+	ctx.Accept = context.AcceptStandard
+	ctx.Route = "/api/test"
+	ctx.Metadata = make(map[string]interface{})
+	return ctx
+}