diff --git a/packages/core/src/tools/web-search/index.test.ts b/packages/core/src/tools/web-search/index.test.ts
new file mode 100644
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+++ b/packages/core/src/tools/web-search/index.test.ts
@@ -0,0 +1,276 @@
+/**
+ * @license
+ * Copyright 2025 Qwen
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { WebSearchTool } from './index.js';
+import type { Config } from '../../config/config.js';
+import type { WebSearchConfig } from './types.js';
+import { ApprovalMode } from '../../config/config.js';
+
+describe('WebSearchTool', () => {
+  let mockConfig: Config;
+
+  beforeEach(() => {
+    vi.resetAllMocks();
+    mockConfig = {
+      getApprovalMode: vi.fn(() => ApprovalMode.AUTO_EDIT),
+      setApprovalMode: vi.fn(),
+      getWebSearchConfig: vi.fn(),
+    } as unknown as Config;
+  });
+
+  describe('formatSearchResults', () => {
+    it('should use answer when available and append sources', async () => {
+      const webSearchConfig: WebSearchConfig = {
+        provider: [
+          {
+            type: 'tavily',
+            apiKey: 'test-key',
+          },
+        ],
+        default: 'tavily',
+      };
+
+      (
+        mockConfig.getWebSearchConfig as ReturnType<typeof vi.fn>
+      ).mockReturnValue(webSearchConfig);
+
+      // Mock fetch to return search results with answer
+      global.fetch = vi.fn().mockResolvedValue({
+        ok: true,
+        json: async () => ({
+          query: 'test query',
+          answer: 'This is a concise answer from the search provider.',
+          results: [
+            {
+              title: 'Result 1',
+              url: 'https://example.com/1',
+              content: 'Content 1',
+            },
+            {
+              title: 'Result 2',
+              url: 'https://example.com/2',
+              content: 'Content 2',
+            },
+          ],
+        }),
+      });
+
+      const tool = new WebSearchTool(mockConfig);
+      const invocation = tool.build({ query: 'test query' });
+      const result = await invocation.execute(new AbortController().signal);
+
+      expect(result.llmContent).toContain(
+        'This is a concise answer from the search provider.',
+      );
+      expect(result.llmContent).toContain('Sources:');
+      expect(result.llmContent).toContain(
+        '[1] Result 1 (https://example.com/1)',
+      );
+      expect(result.llmContent).toContain(
+        '[2] Result 2 (https://example.com/2)',
+      );
+    });
+
+    it('should build informative summary when answer is not available', async () => {
+      const webSearchConfig: WebSearchConfig = {
+        provider: [
+          {
+            type: 'google',
+            apiKey: 'test-key',
+            searchEngineId: 'test-engine',
+          },
+        ],
+        default: 'google',
+      };
+
+      (
+        mockConfig.getWebSearchConfig as ReturnType<typeof vi.fn>
+      ).mockReturnValue(webSearchConfig);
+
+      // Mock fetch to return search results without answer
+      global.fetch = vi.fn().mockResolvedValue({
+        ok: true,
+        json: async () => ({
+          items: [
+            {
+              title: 'Google Result 1',
+              link: 'https://example.com/1',
+              snippet: 'This is a helpful snippet from the first result.',
+            },
+            {
+              title: 'Google Result 2',
+              link: 'https://example.com/2',
+              snippet: 'This is a helpful snippet from the second result.',
+            },
+          ],
+        }),
+      });
+
+      const tool = new WebSearchTool(mockConfig);
+      const invocation = tool.build({ query: 'test query' });
+      const result = await invocation.execute(new AbortController().signal);
+
+      // Should contain formatted results with title, snippet, and source
+      expect(result.llmContent).toContain('1. **Google Result 1**');
+      expect(result.llmContent).toContain(
+        'This is a helpful snippet from the first result.',
+      );
+      expect(result.llmContent).toContain('Source: https://example.com/1');
+      expect(result.llmContent).toContain('2. **Google Result 2**');
+      expect(result.llmContent).toContain(
+        'This is a helpful snippet from the second result.',
+      );
+      expect(result.llmContent).toContain('Source: https://example.com/2');
+
+      // Should include web_fetch hint
+      expect(result.llmContent).toContain('web_fetch tool');
+    });
+
+    it('should include optional fields when available', async () => {
+      const webSearchConfig: WebSearchConfig = {
+        provider: [
+          {
+            type: 'tavily',
+            apiKey: 'test-key',
+          },
+        ],
+        default: 'tavily',
+      };
+
+      (
+        mockConfig.getWebSearchConfig as ReturnType<typeof vi.fn>
+      ).mockReturnValue(webSearchConfig);
+
+      // Mock fetch to return results with score and publishedDate
+      global.fetch = vi.fn().mockResolvedValue({
+        ok: true,
+        json: async () => ({
+          query: 'test query',
+          results: [
+            {
+              title: 'Result with metadata',
+              url: 'https://example.com',
+              content: 'Content with metadata',
+              score: 0.95,
+              published_date: '2024-01-15',
+            },
+          ],
+        }),
+      });
+
+      const tool = new WebSearchTool(mockConfig);
+      const invocation = tool.build({ query: 'test query' });
+      const result = await invocation.execute(new AbortController().signal);
+
+      // Should include relevance score
+      expect(result.llmContent).toContain('Relevance: 95%');
+      // Should include published date
+      expect(result.llmContent).toContain('Published: 2024-01-15');
+    });
+
+    it('should handle empty results gracefully', async () => {
+      const webSearchConfig: WebSearchConfig = {
+        provider: [
+          {
+            type: 'google',
+            apiKey: 'test-key',
+            searchEngineId: 'test-engine',
+          },
+        ],
+        default: 'google',
+      };
+
+      (
+        mockConfig.getWebSearchConfig as ReturnType<typeof vi.fn>
+      ).mockReturnValue(webSearchConfig);
+
+      // Mock fetch to return empty results
+      global.fetch = vi.fn().mockResolvedValue({
+        ok: true,
+        json: async () => ({
+          items: [],
+        }),
+      });
+
+      const tool = new WebSearchTool(mockConfig);
+      const invocation = tool.build({ query: 'test query' });
+      const result = await invocation.execute(new AbortController().signal);
+
+      expect(result.llmContent).toContain('No search results found');
+    });
+
+    it('should limit to top 5 results in fallback mode', async () => {
+      const webSearchConfig: WebSearchConfig = {
+        provider: [
+          {
+            type: 'google',
+            apiKey: 'test-key',
+            searchEngineId: 'test-engine',
+          },
+        ],
+        default: 'google',
+      };
+
+      (
+        mockConfig.getWebSearchConfig as ReturnType<typeof vi.fn>
+      ).mockReturnValue(webSearchConfig);
+
+      // Mock fetch to return 10 results
+      const items = Array.from({ length: 10 }, (_, i) => ({
+        title: `Result ${i + 1}`,
+        link: `https://example.com/${i + 1}`,
+        snippet: `Snippet ${i + 1}`,
+      }));
+
+      global.fetch = vi.fn().mockResolvedValue({
+        ok: true,
+        json: async () => ({ items }),
+      });
+
+      const tool = new WebSearchTool(mockConfig);
+      const invocation = tool.build({ query: 'test query' });
+      const result = await invocation.execute(new AbortController().signal);
+
+      // Should only contain first 5 results
+      expect(result.llmContent).toContain('1. **Result 1**');
+      expect(result.llmContent).toContain('5. **Result 5**');
+      expect(result.llmContent).not.toContain('6. **Result 6**');
+      expect(result.llmContent).not.toContain('10. **Result 10**');
+    });
+  });
+
+  describe('validation', () => {
+    it('should throw validation error when query is empty', () => {
+      const tool = new WebSearchTool(mockConfig);
+      expect(() => tool.build({ query: '' })).toThrow(
+        "The 'query' parameter cannot be empty",
+      );
+    });
+
+    it('should throw validation error when provider is empty string', () => {
+      const tool = new WebSearchTool(mockConfig);
+      expect(() => tool.build({ query: 'test', provider: '' })).toThrow(
+        "The 'provider' parameter cannot be empty",
+      );
+    });
+  });
+
+  describe('configuration', () => {
+    it('should return error when web search is not configured', async () => {
+      (
+        mockConfig.getWebSearchConfig as ReturnType<typeof vi.fn>
+      ).mockReturnValue(null);
+
+      const tool = new WebSearchTool(mockConfig);
+      const invocation = tool.build({ query: 'test query' });
+      const result = await invocation.execute(new AbortController().signal);
+
+      expect(result.error?.message).toContain('Web search is disabled');
+      expect(result.llmContent).toContain('Web search is disabled');
+    });
+  });
+});