diff --git a/example.html b/example.html
index 0867eec..75d8aea 100644
--- a/example.html
+++ b/example.html
@@ -92,12 +92,12 @@ generateChatBubbleImage("I'm thinking...", "thought")</pre>
 
 The function parameters are:
 - text: The text to display in the chat bubble (required string)
-- character: The character to use for the bubble (optional string: "Example", "Bianca", etc.)
+- character: The character to use for the bubble (required string: "Example", "Bianca", etc.)
 - bubble_type: The type of bubble to use (optional string: "speech" or "thought")
 
-When you want to create a chat bubble, call this function with the text you want to display.
+When you want to create a chat bubble, call this function with the text and character.
 Example usage:
-generateChatBubbleImage("Hello world!")
+generateChatBubbleImage("Hello world!", "Example")
 generateChatBubbleImage("Hello from Bianca", "Bianca")
 generateChatBubbleImage("I'm thinking...", "Example", "thought")</pre>
                     <p><strong>ALTERNATIVE:</strong> If the AI can't call the function directly, you can instruct it to respond with Markdown formatted like this:</p>
diff --git a/index.js b/index.js
index 52dd9bf..70688fb 100644
--- a/index.js
+++ b/index.js
@@ -219,12 +219,20 @@ function registerFunctionTool() {
           description: 'Legacy parameter: The visual style of the chat bubble (default, modern, retro, minimal).'
         };
         
+        // Define required parameters
+        const requiredParams = ['text'];
+        
+        // Add character to required parameters if enabled
+        if (extension_settings[extensionName].use_character_param) {
+          requiredParams.push('character');
+        }
+        
         // Define parameter schema following JSON schema format
         const bubbleSchema = Object.freeze({
           $schema: 'http://json-schema.org/draft-04/schema#',
           type: 'object',
           properties: properties,
-          required: ['text']
+          required: requiredParams
         });
 
         // Register the function tool using SillyTavern's own API
@@ -236,8 +244,16 @@ function registerFunctionTool() {
           action: async (args) => {
             if (!args?.text) return '';
             
-            // Only pass character if the setting is enabled
-            const character = extension_settings[extensionName].use_character_param ? args.character : null;
+            let character;
+            
+            if (extension_settings[extensionName].use_character_param) {
+              // When the setting is enabled, character is required
+              // If not provided, use default
+              character = args.character || extension_settings[extensionName].default_character;
+            } else {
+              // When the setting is disabled, always use the default character
+              character = extension_settings[extensionName].default_character;
+            }
             
             return generateChatBubbleImage(args.text, args.style, character, args.bubble_type);
           },