GitLab MCP Server

Instructions

Implementation Reference

• tools/reply_to_review_comment.py:12-55 (handler)

  The main handler function that executes the tool logic: extracts arguments, calls the GitLab API to reply to a merge request discussion, formats success/error responses as TextContent.

  async def reply_to_review_comment(gitlab_url, project_id, access_token, args):
      """Reply to a specific discussion thread in a merge request review"""
      logging.info(f"reply_to_review_comment called with args: {args}")
  
      mr_iid = args["merge_request_iid"]
      discussion_id = args["discussion_id"]
      reply_body = args["body"]
  
      try:
          status, response_data, error_text = await reply_to_merge_request_discussion(
              gitlab_url, project_id, access_token, mr_iid, discussion_id, reply_body
          )
  
          if status == 201:
              author_name = response_data.get("author", {}).get("name", "Unknown")
              note_id = response_data.get("id", "unknown")
  
              result = "✅ **Reply posted successfully!**\n\n"
              result += f"**Merge Request**: !{mr_iid}\n"
              result += f"**Discussion ID**: `{discussion_id}`\n"
              result += f"**Note ID**: `{note_id}`\n"
              result += f"**Author**: {author_name}\n"
              reply_preview = reply_body[:100] + ("..." if len(reply_body) > 100 else "")
              result += f"**Reply**: {reply_preview}\n"
  
              return [TextContent(type="text", text=result)]
          else:
              error_msg = "❌ **Error posting reply**\n\n"
              error_msg += f"**Status**: {status}\n"
              error_msg += f"**Error**: {error_text}\n"
              error_msg += f"**MR**: !{mr_iid}\n"
              error_msg += f"**Discussion**: {discussion_id}\n"
  
              return [TextContent(type="text", text=error_msg)]
  
      except Exception as e:
          logging.error(f"Unexpected error in reply_to_review_comment: {e}")
          error_result = "❌ **Unexpected error**\n\n"
          error_result += f"**Error**: {str(e)}\n"
          error_result += f"**MR**: !{mr_iid}\n"
          error_result += f"**Discussion**: {discussion_id}\n"
  
          return [TextContent(type="text", text=error_result)]

• main.py:194-214 (schema)

  Defines the tool schema including input parameters (merge_request_iid, discussion_id, body) for validation in the MCP server list_tools handler.

  Tool(
      name="reply_to_review_comment",
      description=("Reply to a specific discussion thread in a " "merge request review"),
      inputSchema={
          "type": "object",
          "properties": {
              "merge_request_iid": {
                  "type": "integer",
                  "minimum": 1,
                  "description": ("Internal ID of the merge request"),
              },
              "discussion_id": {
                  "type": "string",
                  "description": ("ID of the discussion thread to reply to"),
              },
              "body": {"type": "string", "description": "Content of the reply comment"},
          },
          "required": ["merge_request_iid", "discussion_id", "body"],
          "additionalProperties": False,
      },
  ),

• main.py:332-335 (registration)

  Registers the tool dispatch in the MCP server's call_tool method, mapping the tool name to the handler function call with config injected.

  elif name == "reply_to_review_comment":
      return await reply_to_review_comment(
          self.config["gitlab_url"], self.config["project_id"], self.config["access_token"], arguments
      )