Slack MCP Server

Instructions

Implementation Reference

• slack_mcp/server.py:1031-1076 (handler)

  The send_announcement tool handler, registered via @mcp.tool() decorator. Constructs Block Kit blocks for a formatted announcement including title, message, author, and timestamp, then sends via SlackClient.send_message.

  @mcp.tool()
  async def send_announcement(
      channel: str,
      title: str,
      message: str,
      author: Optional[str] = None,
      timestamp: Optional[str] = None,
      thread_ts: Optional[str] = None
  ) -> str:
      """
      Send a formatted announcement message.
  
      Args:
          channel: Channel ID or name
          title: Announcement title
          message: Main announcement message
          author: Author name (optional)
          timestamp: Custom timestamp (optional)
          thread_ts: Thread timestamp for replies (optional)
      """
      try:
          blocks = [
              BlockKitBuilder.header(f"📢 {title}"),
              BlockKitBuilder.section(message)
          ]
          
          # Add context with author and timestamp
          context_elements = []
          if author:
              context_elements.append(f"*By:* {author}")
          if timestamp:
              context_elements.append(f"*Date:* {timestamp}")
          else:
              context_elements.append(f"*Date:* {datetime.now().strftime('%Y-%m-%d %H:%M')}")
          
          if context_elements:
              blocks.append(BlockKitBuilder.context(context_elements))
          
          fallback_text = f"📢 {title}: {message}"
          
          client = SlackClient()
          result = await client.send_message(channel, fallback_text, thread_ts, blocks)
          return json.dumps(result, indent=2)
      except Exception as e:
          return json.dumps({"error": str(e)}, indent=2)