pkg/aflow: ask LLM to call several tools at the same time

This seems to help a bit with number of round-trips.

Author: dvyukov

pkg/aflow/flow_test.go

@@ -184,7 +184,7 @@ func TestWorkflow(t *testing.T) {
 			if replySeq < 4 {
 				assert.Equal(t, model, "model1")
 				assert.Equal(t, cfg.SystemInstruction, genai.NewContentFromText("You are smarty. baz"+
-					llmOutputsInstruction, genai.RoleUser))
+					llmMultipleToolsInstruction+llmOutputsInstruction, genai.RoleUser))
 				assert.Equal(t, cfg.Temperature, genai.Ptr[float32](0))
 				assert.Equal(t, len(cfg.Tools), 3)
 				assert.Equal(t, cfg.Tools[0].FunctionDeclarations[0].Name, "tool1")
@@ -444,7 +444,7 @@ func TestWorkflow(t *testing.T) {
 			Name:        "smarty",
 			Model:       "model1",
 			Started:     startTime.Add(4 * time.Second),
-			Instruction: "You are smarty. baz" + llmOutputsInstruction,
+			Instruction: "You are smarty. baz" + llmMultipleToolsInstruction + llmOutputsInstruction,
 			Prompt:      "Prompt: baz func-output",
 		},
 		{
@@ -586,7 +586,7 @@ func TestWorkflow(t *testing.T) {
 			Model:       "model1",
 			Started:     startTime.Add(4 * time.Second),
 			Finished:    startTime.Add(17 * time.Second),
-			Instruction: "You are smarty. baz" + llmOutputsInstruction,
+			Instruction: "You are smarty. baz" + llmMultipleToolsInstruction + llmOutputsInstruction,
 			Prompt:      "Prompt: baz func-output",
 			Reply:       "hello, world!",
 			Results: map[string]any{

pkg/aflow/llm_agent.go

@@ -93,6 +93,10 @@ It must be called exactly once before the final reply.
 Ignore results of this tool.
 `
 
+const llmMultipleToolsInstruction = `
+Prefer calling several tools at the same time to save round-trips.
+`
+
 const llmMissingOutputs = `You did not call set-results tool.
 Please call set-results tool to provide results of the analysis.
 `
@@ -210,6 +214,9 @@ func (a *LLMAgent) chat(ctx *Context, cfg *genai.GenerateContentConfig, tools ma
 func (a *LLMAgent) config(ctx *Context) (*genai.GenerateContentConfig, string, map[string]Tool) {
 	instruction := formatTemplate(a.Instruction, ctx.state)
 	toolList := a.Tools
+	if len(toolList) != 0 {
+		instruction += llmMultipleToolsInstruction
+	}
 	if a.Outputs != nil {
 		instruction += llmOutputsInstruction
 		toolList = append(toolList, a.Outputs.tool)