2 files changed, 174 insertions, 0 deletions
diff --git a/packages/cli/src/ui/commands/toolsCommand.test.ts b/packages/cli/src/ui/commands/toolsCommand.test.ts
new file mode 100644
index 00000000..41c5196b
--- /dev/null
+++ b/packages/cli/src/ui/commands/toolsCommand.test.ts
@@ -0,0 +1,108 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, vi } from 'vitest';
+import { toolsCommand } from './toolsCommand.js';
+import { createMockCommandContext } from '../../test-utils/mockCommandContext.js';
+import { MessageType } from '../types.js';
+import { Tool } from '@google/gemini-cli-core';
+
+// Mock tools for testing
+const mockTools = [
+  {
+    name: 'file-reader',
+    displayName: 'File Reader',
+    description: 'Reads files from the local system.',
+    schema: {},
+  },
+  {
+    name: 'code-editor',
+    displayName: 'Code Editor',
+    description: 'Edits code files.',
+    schema: {},
+  },
+] as Tool[];
+
+describe('toolsCommand', () => {
+  it('should display an error if the tool registry is unavailable', async () => {
+    const mockContext = createMockCommandContext({
+      services: {
+        config: {
+          getToolRegistry: () => Promise.resolve(undefined),
+        },
+      },
+    });
+
+    if (!toolsCommand.action) throw new Error('Action not defined');
+    await toolsCommand.action(mockContext, '');
+
+    expect(mockContext.ui.addItem).toHaveBeenCalledWith(
+      {
+        type: MessageType.ERROR,
+        text: 'Could not retrieve tool registry.',
+      },
+      expect.any(Number),
+    );
+  });
+
+  it('should display "No tools available" when none are found', async () => {
+    const mockContext = createMockCommandContext({
+      services: {
+        config: {
+          getToolRegistry: () =>
+            Promise.resolve({ getAllTools: () => [] as Tool[] }),
+        },
+      },
+    });
+
+    if (!toolsCommand.action) throw new Error('Action not defined');
+    await toolsCommand.action(mockContext, '');
+
+    expect(mockContext.ui.addItem).toHaveBeenCalledWith(
+      expect.objectContaining({
+        text: expect.stringContaining('No tools available'),
+      }),
+      expect.any(Number),
+    );
+  });
+
+  it('should list tools without descriptions by default', async () => {
+    const mockContext = createMockCommandContext({
+      services: {
+        config: {
+          getToolRegistry: () =>
+            Promise.resolve({ getAllTools: () => mockTools }),
+        },
+      },
+    });
+
+    if (!toolsCommand.action) throw new Error('Action not defined');
+    await toolsCommand.action(mockContext, '');
+
+    const message = (mockContext.ui.addItem as vi.Mock).mock.calls[0][0].text;
+    expect(message).not.toContain('Reads files from the local system.');
+    expect(message).toContain('File Reader');
+    expect(message).toContain('Code Editor');
+  });
+
+  it('should list tools with descriptions when "desc" arg is passed', async () => {
+    const mockContext = createMockCommandContext({
+      services: {
+        config: {
+          getToolRegistry: () =>
+            Promise.resolve({ getAllTools: () => mockTools }),
+        },
+      },
+    });
+
+    if (!toolsCommand.action) throw new Error('Action not defined');
+    await toolsCommand.action(mockContext, 'desc');
+
+    const message = (mockContext.ui.addItem as vi.Mock).mock.calls[0][0].text;
+    expect(message).toContain('Reads files from the local system.');
+    expect(message).toContain('Edits code files.');
+  });
+});
diff --git a/packages/cli/src/ui/commands/toolsCommand.ts b/packages/cli/src/ui/commands/toolsCommand.ts
new file mode 100644
index 00000000..f65edd07
--- /dev/null
+++ b/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());
+  },
+};