Reddit MCP Server

Instructions

Implementation Reference

• src/services/reddit-api.ts:335-350 (handler)

  Core handler function that executes the Reddit API request for subreddit posts using makeRequest method.
  async getSubredditPosts( subreddit: string, sort: "hot" | "new" | "top" | "rising" | "controversial" = "hot", limit: number = 25, time?: "hour" | "day" | "week" | "month" | "year" | "all", ): Promise<ApiCallResult> { const params: Record<string, any> = { limit }; if (time && (sort === "top" || sort === "controversial")) { params.t = time; } return this.makeRequest<{ data: { children: Array<{ data: RedditPost }> } }>( `/r/${subreddit}/${sort}.json`, params, ); }
• src/index.ts:426-467 (registration)

  MCP tool registration for 'get_subreddit_posts' including description, schema reference, and handler wrapper.
  server.tool( "get_subreddit_posts", "📖 Get posts from a subreddit\n" + "🎯 What it does: Fetches posts from any Reddit subreddit with sorting options\n" + "📝 Required: subreddit name (e.g., 'programming', 'AskReddit', 'MachineLearning')\n" + "⚙️ Optional: sort ('hot', 'new', 'top')\n" + "💡 Examples:\n" + " • Get hot posts: {\"subreddit\": \"programming\"}\n" + " • Get new posts: {\"subreddit\": \"AskReddit\", \"sort\": \"new\"}\n" + " • Get top posts: {\"subreddit\": \"MachineLearning\", \"sort\": \"top\"}\n" + "🔍 Output: Formatted list with title, author, score, comments, date, and Reddit link", SimpleSubredditPostsSchema.shape, createToolHandler(async (params: z.infer<typeof SimpleSubredditPostsSchema>) => { const { subreddit, sort } = params; // 🧠 Smart defaults for missing parameters const smartDefaults = getSmartDefaults(params, 'subreddit_posts'); const finalParams = { ...smartDefaults, subreddit, sort: sort || smartDefaults.sort }; const result = await redditAPI.getSubredditPosts( finalParams.subreddit, finalParams.sort, finalParams.limit, finalParams.time as any ); // ✅ DRY: Sử dụng validateApiResponse helper const posts = validateApiResponse(result, "posts"); if (posts.length === 0) { return createSuccessResponse(`No posts found in r/${subreddit}`); } const summary = `📊 Found ${posts.length} posts from r/${subreddit} (sorted by ${sort})`; // ✅ DRY: Sử dụng formatDataList helper const postDetails = formatDataList(posts, formatRedditPost, POST_PREVIEW_LIMIT, "posts"); const resultText = `${summary}\n\n${postDetails}`; return createSuccessResponse(resultText); }) );
• src/types/index.ts:96-98 (schema)

  Zod input schema defining parameters: subreddit (required string) and sort (optional enum: hot/new/top).
  export const SimpleSubredditPostsSchema = z.object({ subreddit: z.string().describe("Subreddit name (e.g., 'programming', 'AskReddit')"), sort: z.enum(["hot", "new", "top"]).default("hot").describe("Sort order (default: hot)")
• src/index.ts:78-112 (helper)

  Helper function to format individual Reddit post data into readable markdown text with emojis and details, used in tool output.
  function formatRedditPost(post: RedditPost): string { const title = post.title || 'No title'; const author = post.author || 'Unknown'; const subreddit = post.subreddit || 'Unknown'; const score = post.score || 0; const comments = post.num_comments || 0; const upvoteRatio = post.upvote_ratio ? `${(post.upvote_ratio * 100).toFixed(1)}%` : 'N/A'; // Format creation date const createdDate = post.created_utc ? new Date(post.created_utc * 1000).toLocaleDateString() : 'Unknown'; // Format score with emoji const scoreEmoji = score > HIGH_SCORE_THRESHOLD ? '🔥' : score > MEDIUM_SCORE_THRESHOLD ? '👍' : score > 0 ? '⬆️' : '➡️'; let result = `📝 **${title}**\n`; result += `👤 by u/${author} in r/${subreddit}\n`; result += `${scoreEmoji} Score: ${score.toLocaleString()} | 💬 Comments: ${comments.toLocaleString()} | ⬆️ Upvote Ratio: ${upvoteRatio}\n`; result += `📅 Created: ${createdDate}\n`; // Add post content preview if available if (post.selftext && post.selftext.length > 0) { const preview = post.selftext.length > 200 ? post.selftext.substring(0, 200) + '...' : post.selftext; result += `📄 Content: ${preview}\n`; } // Add URL if it's a link post if (!post.is_self && post.url) { result += `🔗 Link: ${post.url}\n`; } // Add permalink result += `🔗 Reddit: https://reddit.com${post.permalink}\n`; return result; }
• src/services/reddit-api.ts:251-330 (helper)

  Core helper method for making authenticated GET requests to Reddit API, handles OAuth, rate limiting, and returns standardized ApiCallResult.
  private async makeRequest<T>( endpoint: string, params: Record<string, any> = {}, ): Promise<ApiCallResult> { try { const accessToken = await this.getAccessToken(); // Build URL with parameters const url = new URL(`https://oauth.reddit.com${endpoint}`); Object.entries(params).forEach(([key, value]) => { if (value !== undefined && value !== null) { url.searchParams.append(key, value.toString()); } }); // Make the request const response = await fetch(url.toString(), { method: "GET", headers: { "Authorization": `Bearer ${accessToken}`, "User-Agent": this.userAgent, }, signal: AbortSignal.timeout(this.timeout), }); // Handle rate limiting const remaining = response.headers.get('x-ratelimit-remaining'); const reset = response.headers.get('x-ratelimit-reset'); if (remaining) { this.rateLimitRemaining = parseInt(remaining); } if (reset) { this.rateLimitReset = parseInt(reset); } // Check if we're approaching rate limit if (this.rateLimitRemaining < 5) { // Rate limit warning: ${this.rateLimitRemaining} requests remaining } if (!response.ok) { const errorText = await response.text(); // Handle rate limit exceeded if (response.status === 429) { const waitTime = this.rateLimitReset > 0 ? this.rateLimitReset : 60; return { success: false, error: `Rate limit exceeded. Please wait ${waitTime} seconds before trying again.`, endpoint, timestamp: Date.now(), }; } return { success: false, error: `Reddit API Error ${response.status}: ${errorText}`, endpoint, timestamp: Date.now(), }; } const data = await response.json(); return { success: true, data, endpoint, timestamp: Date.now(), }; } catch (error) { return { success: false, error: error instanceof Error ? error.message : "Unknown error", endpoint, timestamp: Date.now(), }; } }