RAG Documentation MCP Server

Instructions

Implementation Reference

• src/handlers/extract-urls.ts:14-108 (handler)

  The ExtractUrlsHandler class implements the core execution logic for the 'extract_urls' tool. It uses browser automation to load the page, cheerio to parse HTML, extracts and filters links based on base path (e.g., for documentation sections), and optionally appends them to a queue file.

  export class ExtractUrlsHandler extends BaseHandler {
    async handle(args: any): Promise<McpToolResponse> {
      if (!args.url || typeof args.url !== 'string') {
        throw new McpError(ErrorCode.InvalidParams, 'URL is required');
      }
  
      await this.apiClient.initBrowser();
      const page = await this.apiClient.browser.newPage();
  
      try {
        const baseUrl = new URL(args.url);
        const basePath = baseUrl.pathname.split('/').slice(0, 3).join('/'); // Get the base path (e.g., /3/ for Python docs)
  
        await page.goto(args.url, { waitUntil: 'networkidle' });
        const content = await page.content();
        const $ = cheerio.load(content);
        const urls = new Set<string>();
  
        $('a[href]').each((_, element) => {
          const href = $(element).attr('href');
          if (href) {
            try {
              const url = new URL(href, args.url);
              // Only include URLs from the same documentation section
              if (url.hostname === baseUrl.hostname && 
                  url.pathname.startsWith(basePath) && 
                  !url.hash && 
                  !url.href.endsWith('#')) {
                urls.add(url.href);
              }
            } catch (e) {
              // Ignore invalid URLs
            }
          }
        });
  
        const urlArray = Array.from(urls);
  
        if (args.add_to_queue) {
          try {
            // Ensure queue file exists
            try {
              await fs.access(QUEUE_FILE);
            } catch {
              await fs.writeFile(QUEUE_FILE, '');
            }
  
            // Append URLs to queue
            const urlsToAdd = urlArray.join('\n') + (urlArray.length > 0 ? '\n' : '');
            await fs.appendFile(QUEUE_FILE, urlsToAdd);
  
            return {
              content: [
                {
                  type: 'text',
                  text: `Successfully added ${urlArray.length} URLs to the queue`,
                },
              ],
            };
          } catch (error) {
            return {
              content: [
                {
                  type: 'text',
                  text: `Failed to add URLs to queue: ${error}`,
                },
              ],
              isError: true,
            };
          }
        }
  
        return {
          content: [
            {
              type: 'text',
              text: urlArray.join('\n') || 'No URLs found on this page.',
            },
          ],
        };
      } catch (error) {
        return {
          content: [
            {
              type: 'text',
              text: `Failed to extract URLs: ${error}`,
            },
          ],
          isError: true,
        };
      } finally {
        await page.close();
      }
    }
  }

• src/handler-registry.ts:77-95 (schema)

  The tool definition including name, description, and input schema (url required string, add_to_queue optional boolean) used when listing tools via MCP protocol.

  {
    name: 'extract_urls',
    description: 'Extract and analyze all URLs from a given web page. This tool crawls the specified webpage, identifies all hyperlinks, and optionally adds them to the processing queue. Useful for discovering related documentation pages, API references, or building a documentation graph. Handles various URL formats and validates links before extraction.',
    inputSchema: {
      type: 'object',
      properties: {
        url: {
          type: 'string',
          description: 'The complete URL of the webpage to analyze (must include protocol, e.g., https://). The page must be publicly accessible.',
        },
        add_to_queue: {
          type: 'boolean',
          description: 'If true, automatically add extracted URLs to the processing queue for later indexing. This enables recursive documentation discovery. Use with caution on large sites to avoid excessive queuing.',
          default: false,
        },
      },
      required: ['url'],
    },
  } as ToolDefinition,

• src/handler-registry.ts:41-41 (registration)

  Registers the ExtractUrlsHandler instance in the handlers Map under the key 'extract_urls' during setup.

  this.handlers.set('extract_urls', new ExtractUrlsHandler(this.server, this.apiClient));