MCP Server for Slack

Instructions

Implementation Reference

• index.ts:449-465 (handler)

  Executes the slack_reply_to_thread tool by validating input arguments and invoking the SlackClient.postReply method to send the reply via Slack API.
  case "slack_reply_to_thread": { const args = request.params .arguments as unknown as ReplyToThreadArgs; if (!args.channel_id || !args.thread_ts || !args.text) { throw new Error( "Missing required arguments: channel_id, thread_ts, and text", ); } const response = await slackClient.postReply( args.channel_id, args.thread_ts, args.text, ); return { content: [{ type: "text", text: JSON.stringify(response) }], }; }
• index.ts:93-114 (schema)

  Defines the Tool object for slack_reply_to_thread, including name, description, and input schema with required parameters: channel_id, thread_ts, text.
  const replyToThreadTool: Tool = { name: "slack_reply_to_thread", description: "Reply to a specific message thread in Slack", inputSchema: { type: "object", properties: { channel_id: { type: "string", description: "The ID of the channel containing the thread", }, thread_ts: { type: "string", description: "The timestamp of the parent message in the format '1234567890.123456'. Timestamps in the format without the period can be converted by adding the period such that 6 numbers come after it.", }, text: { type: "string", description: "The reply text", }, }, required: ["channel_id", "thread_ts", "text"], }, };
• index.ts:286-302 (helper)

  SlackClient method that makes the HTTP POST request to Slack's chat.postMessage API to reply to a thread, using the provided channel_id, thread_ts, and text.
  async postReply( channel_id: string, thread_ts: string, text: string, ): Promise<any> { const response = await fetch("https://slack.com/api/chat.postMessage", { method: "POST", headers: this.botHeaders, body: JSON.stringify({ channel: channel_id, thread_ts: thread_ts, text: text, }), }); return response.json(); }
• index.ts:567-582 (registration)

  Registers the slack_reply_to_thread tool (as replyToThreadTool) in the list of available tools returned by the ListToolsRequest handler.
  server.setRequestHandler(ListToolsRequestSchema, async () => { console.log("Received ListToolsRequest"); return { tools: [ listChannelsTool, postMessageTool, replyToThreadTool, addReactionTool, getChannelHistoryTool, getThreadRepliesTool, getUsersTool, getUserProfileTool, lookupUserByEmailTool, ], }; });
• index.ts:22-26 (schema)

  TypeScript interface defining the input arguments for the slack_reply_to_thread tool, used for type checking in the handler.
  interface ReplyToThreadArgs { channel_id: string; thread_ts: string; text: string; }