MCP Web Research Server

Instructions

Implementation Reference

• index.ts:959-1053 (handler)

  Main handler logic for the 'visit_page' tool: validates URL, navigates to page, extracts markdown content using helpers, optionally takes and saves screenshot, stores result in session, returns JSON with content and screenshot URI.

  case "visit_page": {
      // Extract URL and screenshot flag from request
      const { url, takeScreenshot } = request.params.arguments as {
          url: string;                    // Target URL to visit
          takeScreenshot?: boolean;       // Optional screenshot flag
      };
  
      // Step 1: Validate URL format and security
      if (!isValidUrl(url)) {
          return {
              content: [{
                  type: "text" as const,
                  text: `Invalid URL: ${url}. Only http and https protocols are supported.`
              }],
              isError: true
          };
      }
  
      try {
          // Step 2: Visit page and extract content with retry mechanism
          const result = await withRetry(async () => {
              // Navigate to target URL safely
              await safePageNavigation(page, url);
              const title = await page.title();
  
              // Step 3: Extract and process page content
              const content = await withRetry(async () => {
                  // Convert page content to markdown
                  const extractedContent = await extractContentAsMarkdown(page);
  
                  // If no content is extracted, throw an error
                  if (!extractedContent) {
                      throw new Error('Failed to extract content');
                  }
  
                  // Return the extracted content
                  return extractedContent;
              });
  
              // Step 4: Create result object with page data
              const pageResult: ResearchResult = {
                  url,      // Original URL
                  title,    // Page title
                  content,  // Markdown content
                  timestamp: new Date().toISOString(),  // Capture time
              };
  
              // Step 5: Take screenshot if requested
              let screenshotUri: string | undefined;
              if (takeScreenshot) {
                  // Capture and process screenshot
                  const screenshot = await takeScreenshotWithSizeLimit(page);
                  pageResult.screenshotPath = await saveScreenshot(screenshot, title);
  
                  // Get the index for the resource URI
                  const resultIndex = currentSession ? currentSession.results.length : 0;
                  screenshotUri = `research://screenshots/${resultIndex}`;
  
                  // Notify clients about new screenshot resource
                  server.notification({
                      method: "notifications/resources/list_changed"
                  });
              }
  
              // Step 6: Store result in session
              addResult(pageResult);
              return { pageResult, screenshotUri };
          });
  
          // Step 7: Return formatted result with screenshot URI if taken
          const response: ToolResult = {
              content: [{
                  type: "text" as const,
                  text: JSON.stringify({
                      url: result.pageResult.url,
                      title: result.pageResult.title,
                      content: result.pageResult.content,
                      timestamp: result.pageResult.timestamp,
                      screenshot: result.screenshotUri ? `View screenshot via *MCP Resources* (Paperclip icon) @ URI: ${result.screenshotUri}` : undefined
                  }, null, 2)
              }]
          };
  
          return response;
      } catch (error) {
          // Handle and format page visit errors
          return {
              content: [{
                  type: "text" as const,
                  text: `Failed to visit page: ${(error as Error).message}`
              }],
              isError: true
          };
      }
  }

• index.ts:144-154 (schema)

  Input schema and description for the visit_page tool defined in the TOOLS array.

  {
      name: "visit_page",
      description: "Visit a webpage and extract its content",
      inputSchema: {
          type: "object",
          properties: {
              url: { type: "string", description: "URL to visit" },
              takeScreenshot: { type: "boolean", description: "Whether to take a screenshot" },
          },
          required: ["url"],
      },

• index.ts:580-582 (registration)

  Registration of the tools list (including visit_page) via handler for ListToolsRequestSchema.

  server.setRequestHandler(ListToolsRequestSchema, async () => ({
      tools: TOOLS  // Return list of available research tools
  }));

• index.ts:390-476 (helper)

  Helper function for safe page navigation used in visit_page, handles consent, validation, bot detection.

  async function safePageNavigation(page: Page, url: string): Promise<void> {
      try {
          // Step 1: Set cookies to bypass consent banner
          await page.context().addCookies([{
              name: 'CONSENT',
              value: 'YES+',
              domain: '.google.com',
              path: '/'
          }]);
  
          // Step 2: Initial navigation
          const response = await page.goto(url, {
              waitUntil: 'domcontentloaded',
              timeout: 15000
          });
  
          // Step 3: Basic response validation
          if (!response) {
              throw new Error('Navigation failed: no response received');
          }
  
          // Check HTTP status code; if 400 or higher, throw an error
          const status = response.status();
          if (status >= 400) {
              throw new Error(`HTTP ${status}: ${response.statusText()}`);
          }
  
          // Step 4: Wait for network to become idle or timeout
          await Promise.race([
              page.waitForLoadState('networkidle', { timeout: 5000 })
                  .catch(() => {/* ignore timeout */ }),
              // Fallback timeout in case networkidle never occurs
              new Promise(resolve => setTimeout(resolve, 5000))
          ]);
  
          // Step 5: Security and content validation
          const validation = await page.evaluate(() => {
              const botProtectionExists = [
                  '#challenge-running',     // Cloudflare
                  '#cf-challenge-running',  // Cloudflare
                  '#px-captcha',            // PerimeterX
                  '#ddos-protection',       // Various
                  '#waf-challenge-html'     // Various WAFs
              ].some(selector => document.querySelector(selector));
  
              // Check for suspicious page titles
              const suspiciousTitle = [
                  'security check',
                  'ddos protection',
                  'please wait',
                  'just a moment',
                  'attention required'
              ].some(phrase => document.title.toLowerCase().includes(phrase));
  
              // Count words in the page content
              const bodyText = document.body.innerText || '';
              const words = bodyText.trim().split(/\s+/).length;
  
              // Return validation results
              return {
                  wordCount: words,
                  botProtection: botProtectionExists,
                  suspiciousTitle,
                  title: document.title
              };
          });
  
          // If bot protection is detected, throw an error
          if (validation.botProtection) {
              throw new Error('Bot protection detected');
          }
  
          // If the page title is suspicious, throw an error
          if (validation.suspiciousTitle) {
              throw new Error(`Suspicious page title detected: "${validation.title}"`);
          }
  
          // If the page contains insufficient content, throw an error
          if (validation.wordCount < 10) {
              throw new Error('Page contains insufficient content');
          }
  
      } catch (error) {
          // If an error occurs during navigation, throw an error with the URL and the error message
          throw new Error(`Navigation to ${url} failed: ${(error as Error).message}`);
      }
  }

• index.ts:717-810 (helper)

  Core helper for extracting and converting page HTML to clean Markdown, called by visit_page handler.

  async function extractContentAsMarkdown(
      page: Page,        // Puppeteer page to extract from
      selector?: string  // Optional CSS selector to target specific content
  ): Promise<string> {
      // Step 1: Execute content extraction in browser context
      const html = await page.evaluate((sel) => {
          // Handle case where specific selector is provided
          if (sel) {
              const element = document.querySelector(sel);
              // Return element content or empty string if not found
              return element ? element.outerHTML : '';
          }
  
          // Step 2: Try standard content containers first
          const contentSelectors = [
              'main',           // HTML5 semantic main content
              'article',        // HTML5 semantic article content
              '[role="main"]',  // ARIA main content role
              '#content',       // Common content ID
              '.content',       // Common content class
              '.main',          // Alternative main class
              '.post',          // Blog post content
              '.article',       // Article content container
          ];
  
          // Try each selector in priority order
          for (const contentSelector of contentSelectors) {
              const element = document.querySelector(contentSelector);
              if (element) {
                  return element.outerHTML;  // Return first matching content
              }
          }
  
          // Step 3: Fallback to cleaning full body content
          const body = document.body;
  
          // Define elements to remove for cleaner content
          const elementsToRemove = [
              // Navigation elements
              'header',                    // Page header
              'footer',                    // Page footer
              'nav',                       // Navigation sections
              '[role="navigation"]',       // ARIA navigation elements
  
              // Sidebars and complementary content
              'aside',                     // Sidebar content
              '.sidebar',                  // Sidebar by class
              '[role="complementary"]',    // ARIA complementary content
  
              // Navigation-related elements
              '.nav',                      // Navigation classes
              '.menu',                     // Menu elements
  
              // Page structure elements
              '.header',                   // Header classes
              '.footer',                   // Footer classes
  
              // Advertising and notices
              '.advertisement',            // Advertisement containers
              '.ads',                      // Ad containers
              '.cookie-notice',            // Cookie consent notices
          ];
  
          // Remove each unwanted element from content
          elementsToRemove.forEach(sel => {
              body.querySelectorAll(sel).forEach(el => el.remove());
          });
  
          // Return cleaned body content
          return body.outerHTML;
      }, selector);
  
      // Step 4: Handle empty content case
      if (!html) {
          return '';
      }
  
      try {
          // Step 5: Convert HTML to Markdown
          const markdown = turndownService.turndown(html);
  
          // Step 6: Clean up and format markdown
          return markdown
              .replace(/\n{3,}/g, '\n\n')  // Replace excessive newlines with double
              .replace(/^- $/gm, '')       // Remove empty list items
              .replace(/^\s+$/gm, '')      // Remove whitespace-only lines
              .trim();                     // Remove leading/trailing whitespace
  
      } catch (error) {
          // Log conversion errors and return original HTML as fallback
          console.error('Error converting HTML to Markdown:', error);
          return html;
      }
  }