Configure the tool_choice option to use a specific tool

pkg/common/tools_utils.go

@@ -18,9 +18,11 @@ package common
 
 import (
 	"encoding/json"
+	"errors"
 	"fmt"
 
 	openaiserverapi "github.com/llm-d/llm-d-inference-sim/pkg/openai-server-api"
+	"github.com/openai/openai-go/v3/packages/param"
 	"github.com/santhosh-tekuri/jsonschema/v5"
 )
 
@@ -52,50 +54,125 @@ var fakeStringArguments = []string{
 	`lifetime`,
 }
 
-// CreateToolCalls creates and returns response payload based on this request
-// (tool calls or nothing in case we randomly choose not to generate calls),
-// and the number of generated completion token sand the finish reason
-func CreateToolCalls(tools []openaiserverapi.Tool, toolChoice string, config *Configuration) ([]openaiserverapi.ToolCall, int, error) {
-	// This function is called if tool choice is either 'required' or 'auto'.
-	// In case of 'required' at least one tool call has to be created, and we randomly choose
-	// the number of calls starting from one. Otherwise, we start from 0, and in case we randomly
-	// choose the number of calls to be 0, response text will be generated instead of a tool call.
-	min := 0
-	if toolChoice == ToolChoiceRequired {
-		min = 1
-	}
-	numberOfCalls := RandomInt(min, len(tools))
-	if numberOfCalls == 0 {
-		return nil, 0, nil
+// IsToolChoiceNone checks if the tool_choice is set to "none".
+func IsToolChoiceNone(toolChoice openaiserverapi.ToolChoice) bool {
+	if !param.IsOmitted(toolChoice.OfAuto) {
+		val := toolChoice.OfAuto.Or("")
+		return val == ToolChoiceNone
 	}
+	return false
+}
 
-	calls := make([]openaiserverapi.ToolCall, 0)
-	for i := range numberOfCalls {
-		// Randomly choose which tools to call. We may call the same tool more than once.
-		index := RandomInt(0, len(tools)-1)
-		args, err := generateToolArguments(tools[index], config)
-		if err != nil {
-			return nil, 0, err
+// CreateToolCalls creates and returns tool calls based on the request's tool
+// definitions and the tool_choice parameter.
+//
+// The [tool_choice](https://platform.openai.com/docs/guides/function-calling#tool-choice)
+// parameter controls how the model responds to function calls.
+//
+// This function handles the following cases for tool_choice:
+//   - "none": The model will not call any tools. In this scenario, this function
+//     should ideally be bypassed, as no tool calls will be generated.
+//   - "auto": This is the default behavior where the model autonomously decides
+//     whether to generate a message or call one or more tools from the provided list.
+//   - "required": The model is constrained to call one or more of the available tools.
+//   - Forced Function: A specific tool can be forced by providing an object with the
+//     structure `{"type": "function", "function": {"name": "my_function"}}`.
+//     The model will be restricted to calling only that specified tool.
+//
+// This function currently does not handle the following `tool_choice` scenarios:
+//   - Forced Custom Tool: If `tool_choice` is set to `{"type": "custom", "name": "my_custom"}`,
+//     this function will not be able to enforce the calling of a custom tool, as custom
+//     tool types are not yet supported.
+//   - Allowed Tools Subset: The functionality to restrict the model's tool-calling
+//     capabilities to a specific subset of the available tools has not been implemented.
+//
+// This function returns the generated tool calls, the number of completion
+// tokens used, and an error if one occurs (e.g., if a specified tool is not found).
+func CreateToolCalls(
+	tools []openaiserverapi.Tool,
+	toolChoice openaiserverapi.ToolChoice,
+	config *Configuration,
+) ([]openaiserverapi.ToolCall, int, error) {
+	generateCalls := func(availableTools []openaiserverapi.Tool, minCalls int) ([]openaiserverapi.ToolCall, int, error) {
+		if len(availableTools) == 0 {
+			// If no tools are available to choose from, no calls can be made.
+			return nil, 0, errors.New("no tools available to create tool calls")
 		}
-		argsJson, err := json.Marshal(args)
-		if err != nil {
-			return nil, 0, err
+
+		numberOfCalls := minCalls
+		if len(availableTools) > minCalls {
+			// Randomly decide how many tools to call, between minCalls and the total available.
+			numberOfCalls = RandomInt(minCalls, len(availableTools))
+		}
+
+		if numberOfCalls == 0 {
+			return nil, 0, nil
+		}
+
+		calls := make([]openaiserverapi.ToolCall, 0, numberOfCalls)
+		for i := range numberOfCalls {
+			// Randomly choose which tool to call. We may call the same tool more than once.
+			index := 0
+			if len(availableTools) > 1 {
+				index = RandomInt(0, len(availableTools)-1)
+			}
+			chosenTool := availableTools[index]
+
+			args, err := generateToolArguments(chosenTool, config)
+			if err != nil {
+				return nil, 0, err
+			}
+			argsJson, err := json.Marshal(args)
+			if err != nil {
+				return nil, 0, err
+			}
+
+			call := openaiserverapi.ToolCall{
+				Function: openaiserverapi.FunctionCall{
+					Arguments:          string(argsJson),
+					TokenizedArguments: Tokenize(string(argsJson)),
+					Name:               &chosenTool.Function.Name,
+				},
+				ID:    "chatcmpl-tool-" + RandomNumericString(10),
+				Type:  "function",
+				Index: i,
+			}
+			calls = append(calls, call)
 		}
+		return calls, CountTokensForToolCalls(calls), nil
+	}
+
+	// A specific function is forced.
+	if functionChoice := toolChoice.GetFunction(); functionChoice != nil {
+		requiredFuncName := functionChoice.Name
+		var targetTool *openaiserverapi.Tool
 
-		call := openaiserverapi.ToolCall{
-			Function: openaiserverapi.FunctionCall{
-				Arguments:          string(argsJson),
-				TokenizedArguments: Tokenize(string(argsJson)),
-				Name:               &tools[index].Function.Name,
-			},
-			ID:    "chatcmpl-tool-" + RandomNumericString(10),
-			Type:  "function",
-			Index: i,
+		// Find the specified tool in the list of available tools.
+		for i, tool := range tools {
+			if tool.Function.Name == requiredFuncName {
+				targetTool = &tools[i]
+				break
+			}
 		}
-		calls = append(calls, call)
+
+		if targetTool == nil {
+			return nil, 0, fmt.Errorf("tool with name '%s' requested in tool_choice but not found in the tools list", requiredFuncName)
+		}
+
+		specificTools := []openaiserverapi.Tool{*targetTool}
+
+		// Generate arguments for the specific tool.
+		return generateCalls(specificTools, len(specificTools))
+	}
+
+	// Default behavior for "auto" or "required".
+	// The model can choose from any of the provided tools.
+	min := 0
+	if !param.IsOmitted(toolChoice.OfAuto) && toolChoice.OfAuto.Or("") == ToolChoiceRequired {
+		min = 1
 	}
 
-	return calls, CountTokensForToolCalls(calls), nil
+	return generateCalls(tools, min)
 }
 
 func getRequiredAsMap(property map[string]any) map[string]struct{} {

pkg/llm-d-inference-sim/tools_test.go

@@ -32,11 +32,16 @@ import (
 	"github.com/openai/openai-go/v3/packages/param"
 )
 
+const (
+	functionNameGetWeather     = "get_weather"
+	functionNameGetTemperature = "get_temperature"
+)
+
 var tools = []openai.ChatCompletionToolUnionParam{
 	{
 		OfFunction: &openai.ChatCompletionFunctionToolParam{
 			Function: openai.FunctionDefinitionParam{
-				Name:        "get_weather",
+				Name:        functionNameGetWeather,
 				Description: openai.String("Get weather at the given location"),
 				Parameters: openai.FunctionParameters{
 					"type": "object",
@@ -53,7 +58,7 @@ var tools = []openai.ChatCompletionToolUnionParam{
 	{
 		OfFunction: &openai.ChatCompletionFunctionToolParam{
 			Function: openai.FunctionDefinitionParam{
-				Name:        "get_temperature",
+				Name:        functionNameGetTemperature,
 				Description: openai.String("Get temperature at the given location"),
 				Parameters: openai.FunctionParameters{
 					"type": "object",
@@ -78,7 +83,7 @@ var invalidTools = [][]openai.ChatCompletionToolUnionParam{
 		{
 			OfFunction: &openai.ChatCompletionFunctionToolParam{
 				Function: openai.FunctionDefinitionParam{
-					Name:        "get_weather",
+					Name:        functionNameGetWeather,
 					Description: openai.String("Get weather at the given location"),
 					Parameters: openai.FunctionParameters{
 						"type": "object",
@@ -95,7 +100,7 @@ var invalidTools = [][]openai.ChatCompletionToolUnionParam{
 		{
 			OfFunction: &openai.ChatCompletionFunctionToolParam{
 				Function: openai.FunctionDefinitionParam{
-					Name:        "get_temperature",
+					Name:        functionNameGetTemperature,
 					Description: openai.String("Get temperature at the given location"),
 					Parameters: openai.FunctionParameters{
 						"type": "object",
@@ -119,7 +124,7 @@ var invalidTools = [][]openai.ChatCompletionToolUnionParam{
 		{
 			OfFunction: &openai.ChatCompletionFunctionToolParam{
 				Function: openai.FunctionDefinitionParam{
-					Name:        "get_weather",
+					Name:        functionNameGetWeather,
 					Description: openai.String("Get weather at the given location"),
 					Parameters: openai.FunctionParameters{
 						"type": "object",
@@ -139,7 +144,7 @@ var invalidTools = [][]openai.ChatCompletionToolUnionParam{
 		{
 			OfFunction: &openai.ChatCompletionFunctionToolParam{
 				Function: openai.FunctionDefinitionParam{
-					Name:        "get_weather",
+					Name:        functionNameGetWeather,
 					Description: openai.String("Get weather at the given location"),
 				},
 			},
@@ -312,7 +317,7 @@ var toolWithoutRequiredParams = []openai.ChatCompletionToolUnionParam{
 	{
 		OfFunction: &openai.ChatCompletionFunctionToolParam{
 			Function: openai.FunctionDefinitionParam{
-				Name:        "get_temperature",
+				Name:        functionNameGetTemperature,
 				Description: openai.String("Get temperature at the given location"),
 				Parameters: openai.FunctionParameters{
 					"type": "object",
@@ -398,7 +403,7 @@ var _ = Describe("Simulator for request with tools", func() {
 						tc := toolCalls[0]
 						Expect(tc.Index).To(Or(BeNumerically("==", lastIndex), BeNumerically("==", lastIndex+1)))
 						if tc.Index > int64(lastIndex) {
-							Expect(tc.Function.Name).To(Or(Equal("get_weather"), Equal("get_temperature")))
+							Expect(tc.Function.Name).To(Or(Equal(functionNameGetWeather), Equal(functionNameGetTemperature)))
 							lastIndex++
 							args[tc.Function.Name] = []string{tc.Function.Arguments}
 							functionName = tc.Function.Name
@@ -429,7 +434,7 @@ var _ = Describe("Simulator for request with tools", func() {
 				err := json.Unmarshal([]byte(joinedArgs), &argsMap)
 				Expect(err).NotTo(HaveOccurred())
 
-				if functionName == "get_weather" {
+				if functionName == functionNameGetWeather {
 					Expect(joinedArgs).To(ContainSubstring("location"))
 				} else {
 					Expect(joinedArgs).To(ContainSubstring("city"))
@@ -473,14 +478,14 @@ var _ = Describe("Simulator for request with tools", func() {
 			toolCalls := resp.Choices[0].Message.ToolCalls
 			Expect(toolCalls).ToNot(BeEmpty())
 			for _, tc := range toolCalls {
-				Expect(tc.Function.Name).To(Or(Equal("get_weather"), Equal("get_temperature")))
+				Expect(tc.Function.Name).To(Or(Equal(functionNameGetWeather), Equal(functionNameGetTemperature)))
 				Expect(tc.ID).NotTo(BeEmpty())
 				Expect(tc.Type).To(Equal("function"))
 				args := make(map[string]string)
 				err := json.Unmarshal([]byte(tc.Function.Arguments), &args)
 				Expect(err).NotTo(HaveOccurred())
 
-				if tc.Function.Name == "get_weather" {
+				if tc.Function.Name == functionNameGetWeather {
 					Expect(tc.Function.Arguments).To(ContainSubstring("location"))
 				} else {
 					Expect(tc.Function.Arguments).To(ContainSubstring("city"))
@@ -499,6 +504,59 @@ var _ = Describe("Simulator for request with tools", func() {
 		Entry(nil, common.ModeRandom),
 	)
 
+	DescribeTable("no streaming, a specific tool",
+		func(mode string, specificTool string) {
+			ctx := context.TODO()
+			client, err := startServer(ctx, mode)
+			Expect(err).NotTo(HaveOccurred())
+
+			openaiclient, params := getOpenAIClientAndChatParams(client, model, userMessage, false)
+			params.ToolChoice = openai.ToolChoiceOptionFunctionToolChoice(openai.ChatCompletionNamedToolChoiceFunctionParam{
+				Name: specificTool,
+			})
+			params.Tools = tools
+
+			resp, err := openaiclient.Chat.Completions.New(ctx, params)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(resp.Choices).ShouldNot(BeEmpty())
+			Expect(string(resp.Object)).To(Equal(chatCompletionObject))
+
+			Expect(resp.Usage.PromptTokens).To(Equal(userMsgTokens))
+			Expect(resp.Usage.CompletionTokens).To(BeNumerically(">", 0))
+			Expect(resp.Usage.TotalTokens).To(Equal(resp.Usage.PromptTokens + resp.Usage.CompletionTokens))
+
+			content := resp.Choices[0].Message.Content
+			Expect(content).Should(BeEmpty())
+
+			toolCalls := resp.Choices[0].Message.ToolCalls
+			Expect(toolCalls).ToNot(BeEmpty())
+			for _, tc := range toolCalls {
+				Expect(tc.Function.Name).To(Equal(specificTool))
+				Expect(tc.ID).NotTo(BeEmpty())
+				Expect(tc.Type).To(Equal("function"))
+				args := make(map[string]string)
+				err := json.Unmarshal([]byte(tc.Function.Arguments), &args)
+				Expect(err).NotTo(HaveOccurred())
+
+				if tc.Function.Name == functionNameGetWeather {
+					Expect(tc.Function.Arguments).To(ContainSubstring("location"))
+				} else {
+					Expect(tc.Function.Arguments).To(ContainSubstring("city"))
+					Expect(tc.Function.Arguments).To(ContainSubstring("unit"))
+					Expect(args["unit"]).To(Or(Equal("C"), Equal("F")))
+				}
+			}
+		},
+		func(mode string, specificTool string) string {
+			return "mode: " + mode + ", specificTool: " + specificTool
+		},
+		// Call several times because the tools and arguments are chosen randomly
+		Entry(nil, common.ModeRandom, functionNameGetWeather),
+		Entry(nil, common.ModeRandom, functionNameGetTemperature),
+		Entry(nil, common.ModeRandom, functionNameGetWeather),
+		Entry(nil, common.ModeRandom, functionNameGetTemperature),
+	)
+
 	DescribeTable("check validator",
 		func(mode string) {
 			ctx := context.TODO()
@@ -778,7 +836,7 @@ var _ = Describe("Simulator for request with tools", func() {
 			toolCalls := resp.Choices[0].Message.ToolCalls
 			Expect(toolCalls).To(HaveLen(1))
 			tc := toolCalls[0]
-			Expect(tc.Function.Name).To(Equal("get_temperature"))
+			Expect(tc.Function.Name).To(Equal(functionNameGetTemperature))
 			Expect(tc.ID).NotTo(BeEmpty())
 			Expect(tc.Type).To(Equal("function"))
 			args := make(map[string]string)

pkg/llm-d-inference-sim/worker.go

@@ -88,7 +88,7 @@ func (s *VllmSimulator) processRequest(reqCtx *openaiserverapi.CompletionReqCtx)
 	var toolCalls []openaiserverapi.ToolCall
 	var completionTokens int
 	if reqCtx.IsChatCompletion &&
-		req.GetToolChoice() != common.ToolChoiceNone &&
+		!common.IsToolChoiceNone(req.GetToolChoice()) &&
 		req.GetTools() != nil {
 		toolCalls, completionTokens, err =
 			common.CreateToolCalls(req.GetTools(), req.GetToolChoice(), s.config)