googleai: add more model parameters and update comments (#529)

* googleai: update comments and set TopK & TopP parameters

* googlai: align option types with langchain's default

llms/googleai/googleai_llm.go

@@ -64,21 +64,23 @@ func NewGoogleAI(ctx context.Context, opts ...Option) (*GoogleAI, error) {
 	return gi, nil
 }
 
-// Call Implement the call interface for LLM.
+// Call implements the [llms.Model] interface.
 func (g *GoogleAI) Call(ctx context.Context, prompt string, options ...llms.CallOption) (string, error) {
 	return llms.CallLLM(ctx, g, prompt, options...)
 }
 
-// GenerateContent calls the LLM with the provided parts.
+// GenerateContent implements the [llms.Model] interface.
 func (g *GoogleAI) GenerateContent(ctx context.Context, messages []llms.MessageContent, options ...llms.CallOption) (*llms.ContentResponse, error) {
 	if g.CallbacksHandler != nil {
 		g.CallbacksHandler.HandleLLMGenerateContentStart(ctx, messages)
 	}
 
 	opts := llms.CallOptions{
 		Model:       g.opts.defaultModel,
-		MaxTokens:   int(g.opts.defaultMaxTokens),
-		Temperature: float64(g.opts.defaultTemperature),
+		MaxTokens:   g.opts.defaultMaxTokens,
+		Temperature: g.opts.defaultTemperature,
+		TopP:        g.opts.defaultTopP,
+		TopK:        g.opts.defaultTopK,
 	}
 	for _, opt := range options {
 		opt(&opts)
@@ -87,6 +89,8 @@ func (g *GoogleAI) GenerateContent(ctx context.Context, messages []llms.MessageC
 	model := g.client.GenerativeModel(opts.Model)
 	model.SetMaxOutputTokens(int32(opts.MaxTokens))
 	model.SetTemperature(float32(opts.Temperature))
+	model.SetTopP(float32(opts.TopP))
+	model.SetTopK(int32(opts.TopK))
 
 	var response *llms.ContentResponse
 	var err error

llms/googleai/googleai_option.go

@@ -6,8 +6,10 @@ type options struct {
 	apiKey                string
 	defaultModel          string
 	defaultEmbeddingModel string
-	defaultMaxTokens      int32
-	defaultTemperature    float32
+	defaultMaxTokens      int
+	defaultTemperature    float64
+	defaultTopK           int
+	defaultTopP           float64
 }
 
 func defaultOptions() options {
@@ -17,6 +19,8 @@ func defaultOptions() options {
 		defaultEmbeddingModel: "embedding-001",
 		defaultMaxTokens:      256,
 		defaultTemperature:    0.5,
+		defaultTopK:           3,
+		defaultTopP:           0.95,
 	}
 }