Slack MCP Server

Instructions

Implementation Reference

• slack_mcp/server.py:943-978 (handler)

  The handler function for the 'send_code_snippet' MCP tool. It constructs a Slack Block Kit message with a header, optional description, and formatted code block, then sends it to the specified channel. Includes registration via @mcp.tool() decorator. The function signature and docstring define the tool schema.

  @mcp.tool()
  async def send_code_snippet(
      channel: str,
      title: str,
      code: str,
      language: Optional[str] = None,
      description: Optional[str] = None,
      thread_ts: Optional[str] = None
  ) -> str:
      """
      Send a formatted code snippet message.
  
      Args:
          channel: Channel ID or name
          title: Code snippet title
          code: The code content
          language: Programming language for syntax highlighting (optional)
          description: Optional description
          thread_ts: Thread timestamp for replies (optional)
      """
      try:
          blocks = [BlockKitBuilder.header(title)]
          
          if description:
              blocks.append(BlockKitBuilder.section(description))
          
          blocks.append(BlockKitBuilder.code_block(code, language))
          
          fallback_text = f"{title}: {code[:100]}{'...' if len(code) > 100 else ''}"
          
          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)

• slack_mcp/server.py:693-702 (helper)

  Supporting method in BlockKitBuilder class that creates a Slack Block Kit section block containing a mrkdwn-formatted code snippet, used directly by the send_code_snippet handler.

  def code_block(code: str, language: Optional[str] = None) -> Dict[str, Any]:
      """Create a formatted code block."""
      formatted_code = f"```{language + chr(10) if language else ''}{code}```"
      return {
          "type": "section",
          "text": {
              "type": "mrkdwn",
              "text": formatted_code
          }
      }