diff --git a/README.md b/README.md
index 8f2a673..1704e48 100644
--- a/README.md
+++ b/README.md
@@ -48,6 +48,19 @@ app.commands.execute('jupyterlab-cell-diff:show-codemirror', {
 });
 ```
 
+#### Command Arguments
+
+The `jupyterlab-cell-diff:show-codemirror` command accepts the following arguments:
+
+| Argument            | Type      | Required | Description                                                                          |
+| ------------------- | --------- | -------- | ------------------------------------------------------------------------------------ |
+| `cellId`            | `string`  | No       | ID of the cell to show diff for. If not provided, uses the active cell               |
+| `originalSource`    | `string`  | Yes      | Original source code to compare against                                              |
+| `newSource`         | `string`  | Yes      | New source code to compare with                                                      |
+| `showActionButtons` | `boolean` | No       | Whether to show action buttons in the diff widget (default: `true`)                  |
+| `notebookPath`      | `string`  | No       | Path to the notebook containing the cell. If not provided, uses the current notebook |
+| `openDiff`          | `boolean` | No       | Whether to open the diff widget automatically (default: `true`)                      |
+
 ## Uninstall
 
 To remove the extension, execute:
diff --git a/src/plugin.ts b/src/plugin.ts
index c0c9eb4..ed48514 100644
--- a/src/plugin.ts
+++ b/src/plugin.ts
@@ -105,7 +105,8 @@ const codeMirrorPlugin: JupyterFrontEndPlugin<void> = {
                 'Whether to open the diff widget automatically'
               )
             }
-          }
+          },
+          required: ['originalSource', 'newSource']
         }
       },
       execute: async (args: any = {}) => {
@@ -118,6 +119,13 @@ const codeMirrorPlugin: JupyterFrontEndPlugin<void> = {
           openDiff = true
         } = args;
 
+        if (!originalSource || !newSource) {
+          console.error(
+            trans.__('Missing required arguments: originalSource and newSource')
+          );
+          return;
+        }
+
         const currentNotebook = findNotebook(notebookTracker, notebookPath);
         if (!currentNotebook) {
           return;