HackerNews MCP Server

Instructions

Input Schema

Input Schema (JSON Schema)

Implementation Reference

• src/tools/index.ts:203-262 (handler)

  Implements the core logic for the 'search_trending' MCP tool: fetches the top HackerNews stories using hnClient.getTopStories(), retrieves details for the top N posts, filters valid story posts, extracts words from titles (lowercased, non-punctuation, length >= minWordLength, excluding common stopwords and numbers), counts word frequencies, and returns the top 20 trending words with counts and percentage of posts containing them, along with analysis summary.
  async ({ postCount, minWordLength }) => { try { const topStoryIds = await hnClient.getTopStories(); const postsToAnalyze = topStoryIds.slice(0, postCount || 50); const posts = await hnClient.getMultipleItems(postsToAnalyze); const validPosts = posts.filter(post => post && post.title && post.type === "story"); // Extract and count words from titles const wordCounts = new Map<string, number>(); const commonWords = new Set(['the', 'and', 'for', 'are', 'but', 'not', 'you', 'all', 'can', 'had', 'her', 'was', 'one', 'our', 'out', 'day', 'get', 'has', 'him', 'his', 'how', 'its', 'may', 'new', 'now', 'old', 'see', 'two', 'way', 'who', 'boy', 'did', 'man', 'end', 'why', 'let', 'put', 'say', 'she', 'too', 'use']); validPosts.forEach(post => { if (post?.title) { const words = post.title.toLowerCase() .replace(/[^\w\s]/g, ' ') .split(/\s+/) .filter((word: string) => word.length >= (minWordLength || 4) && !commonWords.has(word) && !/^\d+$/.test(word) ); words.forEach((word: string) => { wordCounts.set(word, (wordCounts.get(word) || 0) + 1); }); } }); // Get top trending words const trendingTopics = Array.from(wordCounts.entries()) .sort((a, b) => b[1] - a[1]) .slice(0, 20) .map(([word, count]) => ({ word, count, percentage: ((count / validPosts.length) * 100).toFixed(1) })); return { content: [{ type: "text", text: JSON.stringify({ analysis_summary: { posts_analyzed: validPosts.length, total_unique_words: wordCounts.size, min_word_length: minWordLength }, trending_topics: trendingTopics, timestamp: new Date().toISOString() }, null, 2) }] }; } catch (error) { logger.error("Failed to get trending topics:", error); return { content: [{ type: "text", text: `Error analyzing trending topics: ${error instanceof Error ? error.message : String(error)}` }], isError: true }; } }
• src/tools/index.ts:192-263 (registration)

  Registers the 'search_trending' tool via server.registerTool() within the setupTools function, including title 'Search Trending Topics', description, and Zod inputSchema with optional postCount (10-100, default 50) and minWordLength (3-10, default 4) parameters, linking to the inline handler.
  // Search trending topics server.registerTool( "search_trending", { title: "Search Trending Topics", description: "Find current trending topics and keywords from top HackerNews posts", inputSchema: { postCount: z.number().min(10).max(100).default(50).optional(), minWordLength: z.number().min(3).max(10).default(4).optional() } }, async ({ postCount, minWordLength }) => { try { const topStoryIds = await hnClient.getTopStories(); const postsToAnalyze = topStoryIds.slice(0, postCount || 50); const posts = await hnClient.getMultipleItems(postsToAnalyze); const validPosts = posts.filter(post => post && post.title && post.type === "story"); // Extract and count words from titles const wordCounts = new Map<string, number>(); const commonWords = new Set(['the', 'and', 'for', 'are', 'but', 'not', 'you', 'all', 'can', 'had', 'her', 'was', 'one', 'our', 'out', 'day', 'get', 'has', 'him', 'his', 'how', 'its', 'may', 'new', 'now', 'old', 'see', 'two', 'way', 'who', 'boy', 'did', 'man', 'end', 'why', 'let', 'put', 'say', 'she', 'too', 'use']); validPosts.forEach(post => { if (post?.title) { const words = post.title.toLowerCase() .replace(/[^\w\s]/g, ' ') .split(/\s+/) .filter((word: string) => word.length >= (minWordLength || 4) && !commonWords.has(word) && !/^\d+$/.test(word) ); words.forEach((word: string) => { wordCounts.set(word, (wordCounts.get(word) || 0) + 1); }); } }); // Get top trending words const trendingTopics = Array.from(wordCounts.entries()) .sort((a, b) => b[1] - a[1]) .slice(0, 20) .map(([word, count]) => ({ word, count, percentage: ((count / validPosts.length) * 100).toFixed(1) })); return { content: [{ type: "text", text: JSON.stringify({ analysis_summary: { posts_analyzed: validPosts.length, total_unique_words: wordCounts.size, min_word_length: minWordLength }, trending_topics: trendingTopics, timestamp: new Date().toISOString() }, null, 2) }] }; } catch (error) { logger.error("Failed to get trending topics:", error); return { content: [{ type: "text", text: `Error analyzing trending topics: ${error instanceof Error ? error.message : String(error)}` }], isError: true }; } } );
• src/tools/index.ts:195-201 (schema)

  Input schema definition using Zod for the search_trending tool, specifying postCount: z.number().min(10).max(100).default(50).optional() and minWordLength: z.number().min(3).max(10).default(4).optional().
  { title: "Search Trending Topics", description: "Find current trending topics and keywords from top HackerNews posts", inputSchema: { postCount: z.number().min(10).max(100).default(50).optional(), minWordLength: z.number().min(3).max(10).default(4).optional() }