update /tools to new slash command arch (#4236)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
Co-authored-by: matt korwel <matt.korwel@gmail.com>

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

@@ -0,0 +1,66 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { type CommandContext, type SlashCommand } from './types.js';
+import { MessageType } from '../types.js';
+
+export const toolsCommand: SlashCommand = {
+  name: 'tools',
+  description: 'list available Gemini CLI tools',
+  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;
+    }
+
+    const toolRegistry = await context.services.config?.getToolRegistry();
+    if (!toolRegistry) {
+      context.ui.addItem(
+        {
+          type: MessageType.ERROR,
+          text: 'Could not retrieve tool registry.',
+        },
+        Date.now(),
+      );
+      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));
+
+    let message = 'Available Gemini CLI tools:\n\n';
+
+    if (geminiTools.length > 0) {
+      geminiTools.forEach((tool) => {
+        if (useShowDescriptions && tool.description) {
+          message += `  - \u001b[36m${tool.displayName} (${tool.name})\u001b[0m:\n`;
+
+          const greenColor = '\u001b[32m';
+          const resetColor = '\u001b[0m';
+
+          // Handle multi-line descriptions
+          const descLines = tool.description.trim().split('\n');
+          for (const descLine of descLines) {
+            message += `      ${greenColor}${descLine}${resetColor}\n`;
+          }
+        } else {
+          message += `  - \u001b[36m${tool.displayName}\u001b[0m\n`;
+        }
+      });
+    } else {
+      message += '  No tools available\n';
+    }
+    message += '\n';
+
+    message += '\u001b[0m';
+
+    context.ui.addItem({ type: MessageType.INFO, text: message }, Date.now());
+  },
+};