feat(deep): allow disabling built-in task prompt injection

adk/prebuilt/deep/deep.go

@@ -80,6 +80,8 @@ type TypedConfig[M adk.MessageType] struct {
 	WithoutWriteTodos bool
 	// WithoutGeneralSubAgent disables the general-purpose subagent when set to true.
 	WithoutGeneralSubAgent bool
+	// WithoutTaskPrompt disables the built-in task tool prompt injection when set to true.
+	WithoutTaskPrompt bool
 	// TaskToolDescriptionGenerator allows customizing the description for the task tool.
 	// If provided, this function generates the tool description based on available subagents.
 	TaskToolDescriptionGenerator func(ctx context.Context, availableAgents []adk.TypedAgent[M]) (string, error)
@@ -134,6 +136,7 @@ func NewTyped[M adk.MessageType](ctx context.Context, cfg *TypedConfig[M]) (adk.
 			cfg.SubAgents,
 
 			cfg.WithoutGeneralSubAgent,
+			cfg.WithoutTaskPrompt,
 			cfg.ChatModel,
 			instruction,
 			cfg.ToolsConfig,

adk/prebuilt/deep/deep_test.go

@@ -150,6 +150,88 @@ func TestWriteTodos(t *testing.T) {
 	assert.Equal(t, fmt.Sprintf("Updated todo list to %s", todos), result)
 }
 
+func TestDeepAgentTaskPromptConfig(t *testing.T) {
+	ctx := context.Background()
+
+	tests := []struct {
+		name              string
+		withoutTaskPrompt bool
+		wantTaskPrompt    bool
+	}{
+		{
+			name:           "default injects task prompt",
+			wantTaskPrompt: true,
+		},
+		{
+			name:              "without task prompt keeps task tool",
+			withoutTaskPrompt: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ctrl := gomock.NewController(t)
+			defer ctrl.Finish()
+
+			cm := mockModel.NewMockToolCallingChatModel(ctrl)
+
+			var capturedTools []*schema.ToolInfo
+			cm.EXPECT().WithTools(gomock.Any()).Return(cm, nil).AnyTimes()
+
+			var capturedMessages []*schema.Message
+			cm.EXPECT().Generate(gomock.Any(), gomock.Any(), gomock.Any()).
+				DoAndReturn(func(_ context.Context, msgs []*schema.Message, opts ...model.Option) (*schema.Message, error) {
+					capturedMessages = msgs
+					options := model.GetCommonOptions(&model.Options{}, opts...)
+					capturedTools = options.Tools
+					return schema.AssistantMessage("done", nil), nil
+				}).
+				Times(1)
+
+			agent, err := New(ctx, &Config{
+				Name:                   "deep",
+				Description:            "deep agent",
+				ChatModel:              cm,
+				Instruction:            "you are deep agent",
+				SubAgents:              []adk.Agent{&spySubAgent{}},
+				MaxIteration:           2,
+				WithoutWriteTodos:      true,
+				WithoutGeneralSubAgent: true,
+				WithoutTaskPrompt:      tt.withoutTaskPrompt,
+			})
+			assert.NoError(t, err)
+
+			r := adk.NewRunner(ctx, adk.RunnerConfig{Agent: agent})
+			it := r.Run(ctx, []adk.Message{schema.UserMessage("hi")})
+			for {
+				event, ok := it.Next()
+				if !ok {
+					break
+				}
+				assert.NoError(t, event.Err)
+			}
+
+			assert.NotEmpty(t, capturedMessages)
+			assert.Equal(t, schema.System, capturedMessages[0].Role)
+			assert.Contains(t, capturedMessages[0].Content, "you are deep agent")
+			if tt.wantTaskPrompt {
+				assert.Contains(t, capturedMessages[0].Content, "# 'task' (subagent spawner)")
+			} else {
+				assert.NotContains(t, capturedMessages[0].Content, "# 'task' (subagent spawner)")
+			}
+
+			var hasTaskTool bool
+			for _, toolInfo := range capturedTools {
+				if toolInfo.Name == taskToolName {
+					hasTaskTool = true
+					break
+				}
+			}
+			assert.True(t, hasTaskTool)
+		})
+	}
+}
+
 func TestDeepSubAgentSharesSessionValues(t *testing.T) {
 	ctx := context.Background()
 	spy := &spySubAgent{}

adk/prebuilt/deep/task_tool.go

@@ -38,6 +38,7 @@ func typedTaskToolMiddleware[M adk.MessageType](
 	subAgents []adk.TypedAgent[M],
 
 	withoutGeneralSubAgent bool,
+	withoutTaskPrompt bool,
 	cm model.BaseModel[M],
 	instruction string,
 	toolsConfig adk.ToolsConfig,
@@ -50,10 +51,13 @@ func typedTaskToolMiddleware[M adk.MessageType](
 	if err != nil {
 		return nil, err
 	}
-	prompt := internal.SelectPrompt(internal.I18nPrompts{
-		English: taskPrompt,
-		Chinese: taskPromptChinese,
-	})
+	var prompt string
+	if !withoutTaskPrompt {
+		prompt = internal.SelectPrompt(internal.I18nPrompts{
+			English: taskPrompt,
+			Chinese: taskPromptChinese,
+		})
+	}
 
 	return typedBuildAppendPromptTool[M](prompt, t), nil
 }