feat(cli): expose /tools desc as explicit subcommand for discoverability (#21241)

Co-authored-by: Coco Sheng <cocosheng@google.com>
Co-authored-by: Gaurav <39389231+gsquared94@users.noreply.github.com>

packages/cli/src/ui/commands/toolsCommand.test.ts

@@ -110,4 +110,28 @@ describe('toolsCommand', () => {
     );
     expect(message.tools[1].description).toBe('Edits code files.');
   });
+
+  it('should expose a desc subcommand for TUI discoverability', async () => {
+    const descSubCommand = toolsCommand.subCommands?.find(
+      (cmd) => cmd.name === 'desc',
+    );
+    expect(descSubCommand).toBeDefined();
+    expect(descSubCommand?.description).toContain('descriptions');
+
+    const mockContext = createMockCommandContext({
+      services: {
+        config: {
+          getToolRegistry: () => ({ getAllTools: () => mockTools }),
+        },
+      },
+    });
+
+    if (!descSubCommand?.action) throw new Error('Action not defined');
+    await descSubCommand.action(mockContext, '');
+
+    const [message] = (mockContext.ui.addItem as ReturnType<typeof vi.fn>).mock
+      .calls[0];
+    expect(message.type).toBe(MessageType.TOOLS_LIST);
+    expect(message.showDescriptions).toBe(true);
+  });
 });

packages/cli/src/ui/commands/toolsCommand.ts

@@ -11,43 +11,60 @@ import {
 } from './types.js';
 import { MessageType, type HistoryItemToolsList } from '../types.js';
 
+async function listTools(
+  context: CommandContext,
+  showDescriptions: boolean,
+): Promise<void> {
+  const toolRegistry = context.services.config?.getToolRegistry();
+  if (!toolRegistry) {
+    context.ui.addItem({
+      type: MessageType.ERROR,
+      text: 'Could not retrieve tool registry.',
+    });
+    return;
+  }
+
+  const tools = toolRegistry.getAllTools();
+  // Filter out MCP tools by checking for the absence of a serverName property
+  const geminiTools = tools.filter((tool) => !('serverName' in tool));
+
+  const toolsListItem: HistoryItemToolsList = {
+    type: MessageType.TOOLS_LIST,
+    tools: geminiTools.map((tool) => ({
+      name: tool.name,
+      displayName: tool.displayName,
+      description: tool.description,
+    })),
+    showDescriptions,
+  };
+
+  context.ui.addItem(toolsListItem);
+}
+
+const toolsDescSubCommand: SlashCommand = {
+  name: 'desc',
+  altNames: ['descriptions'],
+  description: 'List available Gemini CLI tools with descriptions.',
+  kind: CommandKind.BUILT_IN,
+  autoExecute: true,
+  action: async (context: CommandContext): Promise<void> =>
+    listTools(context, true),
+};
+
 export const toolsCommand: SlashCommand = {
   name: 'tools',
-  description: 'List available Gemini CLI tools. Usage: /tools [desc]',
+  description:
+    'List available Gemini CLI tools. Use /tools desc to include descriptions.',
   kind: CommandKind.BUILT_IN,
   autoExecute: false,
+  subCommands: [toolsDescSubCommand],
   action: async (context: CommandContext, args?: string): Promise<void> => {
     const subCommand = args?.trim();
 
-    // Default to NOT showing descriptions. The user must opt in with an argument.
-    let useShowDescriptions = false;
-    if (subCommand === 'desc' || subCommand === 'descriptions') {
-      useShowDescriptions = true;
-    }
+    // Keep backward compatibility for typed arguments while exposing desc in TUI via subcommands.
+    const useShowDescriptions =
+      subCommand === 'desc' || subCommand === 'descriptions';
 
-    const toolRegistry = context.services.config?.getToolRegistry();
-    if (!toolRegistry) {
-      context.ui.addItem({
-        type: MessageType.ERROR,
-        text: 'Could not retrieve tool registry.',
-      });
-      return;
-    }
-
-    const tools = toolRegistry.getAllTools();
-    // Filter out MCP tools by checking for the absence of a serverName property
-    const geminiTools = tools.filter((tool) => !('serverName' in tool));
-
-    const toolsListItem: HistoryItemToolsList = {
-      type: MessageType.TOOLS_LIST,
-      tools: geminiTools.map((tool) => ({
-        name: tool.name,
-        displayName: tool.displayName,
-        description: tool.description,
-      })),
-      showDescriptions: useShowDescriptions,
-    };
-
-    context.ui.addItem(toolsListItem);
+    await listTools(context, useShowDescriptions);
   },
 };