reddit-mcp-server

Instructions

Implementation Reference

• src/index.ts:497-532 (registration)

  MCP tool registration for 'create_post', including schema and inline handler function
  server.addTool({ name: "create_post", description: "Create a new post in a subreddit (requires REDDIT_USERNAME and REDDIT_PASSWORD)", parameters: z.object({ subreddit: z.string().describe("The subreddit name (without r/ prefix)"), title: z.string().describe("The post title"), content: z.string().describe("The post content (text for self posts, URL for link posts)"), is_self: z.boolean().default(true).describe("Whether this is a self post (text) or link post"), }), execute: async (args) => { const client = getRedditClient() if (!client) { throw new Error("Reddit client not initialized") } // Check if user credentials are configured if (!process.env.REDDIT_USERNAME || !process.env.REDDIT_PASSWORD) { throw new Error( "User authentication required. Please set REDDIT_USERNAME and REDDIT_PASSWORD environment variables.", ) } const post = await client.createPost(args.subreddit, args.title, args.content, args.is_self) const formattedPost = formatPostInfo(post) return `# Post Created Successfully ## Post Details - Title: ${formattedPost.title} - Subreddit: r/${formattedPost.subreddit} - Type: ${formattedPost.type} - Link: ${formattedPost.links.fullPost} Your post has been successfully submitted to r/${formattedPost.subreddit}.` }, })
• src/client/reddit-client.ts:295-356 (handler)

  Core handler in RedditClient that performs the actual POST /api/submit to Reddit API
  async createPost(subreddit: string, title: string, content: string, isSelf: boolean = true): Promise<RedditPost> { await this.authenticate() if (!this.username || !this.password) { throw new Error("User authentication required for posting") } try { const kind = isSelf ? "self" : "link" const params = new URLSearchParams() params.append("sr", subreddit) params.append("kind", kind) params.append("title", title) params.append(isSelf ? "text" : "url", content) params.append("api_type", "json") // Request standard JSON response format const response = await this.makeRequest("/api/submit", { method: "POST", headers: { "Content-Type": "application/x-www-form-urlencoded", }, body: params.toString(), }) if (!response.ok) { const errorText = await response.text() console.error(`[Reddit API] Create post failed: ${response.status} ${response.statusText}`) console.error(`[Reddit API] Error response: ${errorText}`) throw new Error(`HTTP ${response.status}: ${errorText}`) } const json = (await response.json()) as any console.error(`[Reddit API] Create post response:`, JSON.stringify(json, null, 2)) // With api_type=json, response has json.data.id or json.errors if (json.json?.errors && json.json.errors.length > 0) { const errors = json.json.errors.map((e: any) => e.join(": ")).join(", ") console.error(`[Reddit API] Post creation errors: ${errors}`) throw new Error(`Reddit API errors: ${errors}`) } // Extract post ID from standard JSON response const postId = json.json?.data?.id || json.json?.data?.name?.replace("t3_", "") if (!postId) { console.error(`[Reddit API] No post ID in response`) throw new Error("No post ID returned from Reddit") } console.error(`[Reddit API] Post created with ID: ${postId}`) return await this.getPost(postId, subreddit) } catch (error) { // Log and re-throw the actual error console.error(`[Reddit API] Create post exception:`, error) if (error instanceof Error && error.message.includes("HTTP")) { throw error } throw new Error( `Failed to create post in ${subreddit}: ${error instanceof Error ? error.message : String(error)}`, ) } }
• src/index.ts:500-505 (schema)

  Input schema validation using Zod for the create_post tool parameters
  parameters: z.object({ subreddit: z.string().describe("The subreddit name (without r/ prefix)"), title: z.string().describe("The post title"), content: z.string().describe("The post content (text for self posts, URL for link posts)"), is_self: z.boolean().default(true).describe("Whether this is a self post (text) or link post"), }),