fix(go/plugins/googlegenai): use one FunctionDeclaration for all tools

go/plugins/googlegenai/gemini.go

@@ -429,6 +429,8 @@ func toGeminiRequest(input *ai.ModelRequest, cache *genai.CachedContent) (*genai
 // toGeminiTools translates a slice of [ai.ToolDefinition] to a slice of [genai.Tool].
 func toGeminiTools(inTools []*ai.ToolDefinition) ([]*genai.Tool, error) {
 	var outTools []*genai.Tool
+	functions := []*genai.FunctionDeclaration{}
+
 	for _, t := range inTools {
 		if !validToolName(t.Name) {
 			return nil, fmt.Errorf(`invalid tool name: %q, must start with a letter or an underscore, must be alphanumeric, underscores, dots or dashes with a max length of 64 chars`, t.Name)
@@ -442,8 +444,15 @@ func toGeminiTools(inTools []*ai.ToolDefinition) ([]*genai.Tool, error) {
 			Parameters:  inputSchema,
 			Description: t.Description,
 		}
-		outTools = append(outTools, &genai.Tool{FunctionDeclarations: []*genai.FunctionDeclaration{fd}})
+		functions = append(functions, fd)
 	}
+
+	if len(functions) > 0 {
+		outTools = append(outTools, &genai.Tool{
+			FunctionDeclarations: functions,
+		})
+	}
+
 	return outTools, nil
 }
 

go/plugins/googlegenai/gemini_test.go

@@ -45,6 +45,9 @@ func TestConvertRequest(t *testing.T) {
 			Temperature:     genai.Ptr[float32](0.4),
 			TopK:            genai.Ptr[float32](0.1),
 			TopP:            genai.Ptr[float32](1.0),
+			Tools: []*genai.Tool{
+				{GoogleSearch: &genai.GoogleSearch{}},
+			},
 			ThinkingConfig: &genai.ThinkingConfig{
 				IncludeThoughts: false,
 				ThinkingBudget:  genai.Ptr[int32](0),
@@ -151,6 +154,9 @@ func TestConvertRequest(t *testing.T) {
 		if gcc.ThinkingConfig == nil {
 			t.Errorf("ThinkingConfig should not be empty")
 		}
+		if len(gcc.Tools) != 1 {
+			t.Errorf("tools should have been: 1, got: %d", len(gcc.Tools))
+		}
 	})
 	t.Run("use valid tools outside genkit", func(t *testing.T) {
 		badCfg := genai.GenerateContentConfig{

go/plugins/googlegenai/googleai_live_test.go

@@ -82,6 +82,12 @@ func TestGoogleAILive(t *testing.T) {
 		},
 	)
 
+	answerOfEverythingTool := genkit.DefineTool(g, "answerOfEverything", "use this tool when the user asks for the answer of life, the universe and everything",
+		func(ctx *ai.ToolContext, input any) (int, error) {
+			return 42, nil
+		},
+	)
+
 	t.Run("embedder", func(t *testing.T) {
 		res, err := genkit.Embed(ctx, g, ai.WithEmbedder(embedder), ai.WithTextDocs("yellow banana"))
 		if err != nil {
@@ -191,7 +197,42 @@ func TestGoogleAILive(t *testing.T) {
 			t.Errorf("got %q, expecting it to contain %q", out, want)
 		}
 	})
-
+	t.Run("api side tools", func(t *testing.T) {
+		m := googlegenai.GoogleAIModel(g, "gemini-2.5-flash")
+		_, err := genkit.Generate(ctx, g,
+			ai.WithConfig(&genai.GenerateContentConfig{
+				Tools: []*genai.Tool{
+					{GoogleSearch: &genai.GoogleSearch{}}, {GoogleSearch: &genai.GoogleSearch{}},
+				},
+			}),
+			ai.WithModel(m),
+			ai.WithPrompt("When is the next lunar eclipse in US?"))
+		if err != nil {
+			t.Fatal(err)
+		}
+	})
+	t.Run("api and custom tools", func(t *testing.T) {
+		m := googlegenai.GoogleAIModel(g, "gemini-2.5-flash")
+		resp, err := genkit.Generate(ctx, g,
+			ai.WithConfig(&genai.GenerateContentConfig{
+				Tools: []*genai.Tool{
+					{GoogleSearch: &genai.GoogleSearch{}},
+				},
+			}),
+			ai.WithModel(m),
+			ai.WithTools(gablorkenTool, answerOfEverythingTool),
+			ai.WithPrompt("What is the answer of life?"))
+		if err != nil {
+			t.Fatal(err)
+		}
+		// api tools should not be used when custom tools are present
+		if len(resp.Request.Tools) != 2 {
+			t.Fatalf("got %d tools, want: 2", len(resp.Request.Tools))
+		}
+		if !strings.Contains(resp.Text(), "42") {
+			t.Fatalf("got %s, want: 42", resp.Text())
+		}
+	})
 	t.Run("tool with json output", func(t *testing.T) {
 		type weatherQuery struct {
 			Location string `json:"location"`

go/samples/prompts/main.go

@@ -227,6 +227,12 @@ func PromptWithTool(ctx context.Context, g *genkit.Genkit) {
 		},
 	)
 
+	answerOfEverythingTool := genkit.DefineTool(g, "answerOfEverything", "use this tool when the user asks for the answer of life, the universe and everything",
+		func(ctx *ai.ToolContext, input any) (int, error) {
+			return 42, nil
+		},
+	)
+
 	type Output struct {
 		Gablorken float64 `json:"gablorken"`
 	}
@@ -236,7 +242,7 @@ func PromptWithTool(ctx context.Context, g *genkit.Genkit) {
 		g, "PromptWithTool",
 		ai.WithToolChoice(ai.ToolChoiceAuto),
 		ai.WithMaxTurns(1),
-		ai.WithTools(gablorkenTool),
+		ai.WithTools(gablorkenTool, answerOfEverythingTool),
 		ai.WithOutputType(Output{}),
 		ai.WithPrompt("what is a gablorken of 2 over 3.5?"),
 	)