diff --git a/main.go b/main.go
index f6ba56d..884f88e 100644
--- a/main.go
+++ b/main.go
@@ -218,7 +218,6 @@ func callLLM(prompt string, apiURL string) ([]byte, error) {
 		}
 	}
 
-	client := &http.Client{}
 	maxRetries := 6
 	baseDelay := 2 * time.Second
 
@@ -234,7 +233,7 @@ func callLLM(prompt string, apiURL string) ([]byte, error) {
 			req.Header.Add("Authorization", "Bearer "+cfg.APIToken)
 		}
 
-		resp, err := client.Do(req)
+		resp, err := httpClient.Do(req)
 		if err != nil {
 			if attempt == maxRetries-1 {
 				return nil, fmt.Errorf("LLM call failed after %d retries on client.Do: %w", maxRetries, err)
diff --git a/models/models.go b/models/models.go
index 80cbe2c..18a2a08 100644
--- a/models/models.go
+++ b/models/models.go
@@ -85,3 +85,44 @@ type RPMessage struct {
 	Author  string `json:"author"`
 	Content string `json:"content"`
 }
+
+// === tools models
+
+type ToolArgProps struct {
+	Type        string `json:"type"`
+	Description string `json:"description"`
+}
+
+type ToolFuncParams struct {
+	Type       string                  `json:"type"`
+	Properties map[string]ToolArgProps `json:"properties"`
+	Required   []string                `json:"required"`
+}
+
+type ToolFunc struct {
+	Name        string         `json:"name"`
+	Description string         `json:"description"`
+	Parameters  ToolFuncParams `json:"parameters"`
+}
+
+type Tool struct {
+	Type     string   `json:"type"`
+	Function ToolFunc `json:"function"`
+}
+
+type OpenAIReq struct {
+	*ChatBody
+	Tools []Tool `json:"tools"`
+}
+
+type ChatBody struct {
+	Model    string    `json:"model"`
+	Messages []RoleMsg `json:"messages"`
+}
+
+type RoleMsg struct {
+	Role    string `json:"role"`
+	Content string `json:"content"`
+}
+
+// ===
diff --git a/tools.go b/tools.go
new file mode 100644
index 0000000..fa2dbc7
--- /dev/null
+++ b/tools.go
@@ -0,0 +1,65 @@
+package main
+
+import (
+	"grailbench/models"
+	"time"
+)
+
+func sendEmail(args map[string]string) []byte {
+	logger.Info("send-email is used", "args", args)
+	return nil
+}
+
+func getCurrentTimestamp(args map[string]string) []byte {
+	ts := time.Now()
+	return []byte(ts.Format(time.RFC3339))
+}
+
+type fnSig func(map[string]string) []byte
+
+var fnMap = map[string]fnSig{
+	"get_current_timestamp": getCurrentTimestamp,
+	"send_email":            sendEmail,
+}
+
+// openai style def
+var baseTools = []models.Tool{
+	// get_current_timestamp
+	models.Tool{
+		Type: "function",
+		Function: models.ToolFunc{
+			Name:        "get_current_timestamp",
+			Description: "Returns current timestamp in RFC3999 format",
+			Parameters: models.ToolFuncParams{
+				Type:     "object",
+				Required: []string{},
+			},
+		},
+	},
+	// send_email
+	models.Tool{
+		Type: "function",
+		Function: models.ToolFunc{
+			Name:        "send_email",
+			Description: "Sends email to a provided address with given message.",
+			Parameters: models.ToolFuncParams{
+				Type:     "object",
+				Required: []string{"address", "title", "body"},
+				Properties: map[string]models.ToolArgProps{
+					"address": models.ToolArgProps{
+						Type:        "string",
+						Description: "email address of the recipient",
+					},
+					"title": models.ToolArgProps{
+						Type:        "string",
+						Description: "",
+					},
+					"body": models.ToolArgProps{
+						Type:        "string",
+						Description: "email body, can be in form of html page, markdown or pure text.",
+					},
+				},
+			},
+		},
+	},
+}