MCP Server for Slack

Instructions

Implementation Reference

• index.ts:467-482 (handler)

  Handler for the slack_add_reaction tool within the CallToolRequest switch statement. It validates input arguments and invokes the SlackClient.addReaction method to perform the action.
  case "slack_add_reaction": { const args = request.params.arguments as unknown as AddReactionArgs; if (!args.channel_id || !args.timestamp || !args.reaction) { throw new Error( "Missing required arguments: channel_id, timestamp, and reaction", ); } const response = await slackClient.addReaction( args.channel_id, args.timestamp, args.reaction, ); return { content: [{ type: "text", text: JSON.stringify(response) }], }; }
• index.ts:116-137 (schema)

  Input schema and Tool definition for slack_add_reaction, specifying parameters channel_id, timestamp, and reaction.
  const addReactionTool: Tool = { name: "slack_add_reaction", description: "Add a reaction emoji to a message", inputSchema: { type: "object", properties: { channel_id: { type: "string", description: "The ID of the channel containing the message", }, timestamp: { type: "string", description: "The timestamp of the message to react to", }, reaction: { type: "string", description: "The name of the emoji reaction (without ::)", }, }, required: ["channel_id", "timestamp", "reaction"], }, };
• index.ts:304-320 (helper)

  Core implementation in SlackClient class that makes the HTTP POST request to Slack's reactions.add API endpoint to add the reaction.
  async addReaction( channel_id: string, timestamp: string, reaction: string, ): Promise<any> { const response = await fetch("https://slack.com/api/reactions.add", { method: "POST", headers: this.botHeaders, body: JSON.stringify({ channel: channel_id, timestamp: timestamp, name: reaction, }), }); return response.json(); }
• index.ts:570-580 (registration)

  Registration of the slack_add_reaction tool (referenced as addReactionTool) in the array returned by the ListToolsRequest handler.
  tools: [ listChannelsTool, postMessageTool, replyToThreadTool, addReactionTool, getChannelHistoryTool, getThreadRepliesTool, getUsersTool, getUserProfileTool, lookupUserByEmailTool, ],
• index.ts:28-32 (schema)

  TypeScript interface defining the arguments for the slack_add_reaction tool.
  interface AddReactionArgs { channel_id: string; timestamp: string; reaction: string; }