ServiceNow MCP Server

Instructions

Implementation Reference

• src/servicenow_mcp/tools/change_tools.py:584-666 (handler)

  Main implementation of the add_change_task tool handler. Handles parameter validation using AddChangeTaskParams, constructs the API request to create a change_task in ServiceNow's change_task table, and returns the result.

  def add_change_task(
      auth_manager: AuthManager,
      server_config: ServerConfig,
      params: Dict[str, Any],
  ) -> Dict[str, Any]:
      """
      Add a task to a change request in ServiceNow.
  
      Args:
          auth_manager: The authentication manager.
          server_config: The server configuration.
          params: The parameters for adding a change task.
  
      Returns:
          The created change task.
      """
      # Unwrap and validate parameters
      result = _unwrap_and_validate_params(
          params, 
          AddChangeTaskParams,
          required_fields=["change_id", "short_description"]
      )
      
      if not result["success"]:
          return result
      
      validated_params = result["params"]
      
      # Prepare the request data
      data = {
          "change_request": validated_params.change_id,
          "short_description": validated_params.short_description,
      }
      
      # Add optional fields if provided
      if validated_params.description:
          data["description"] = validated_params.description
      if validated_params.assigned_to:
          data["assigned_to"] = validated_params.assigned_to
      if validated_params.planned_start_date:
          data["planned_start_date"] = validated_params.planned_start_date
      if validated_params.planned_end_date:
          data["planned_end_date"] = validated_params.planned_end_date
      
      # Get the instance URL
      instance_url = _get_instance_url(auth_manager, server_config)
      if not instance_url:
          return {
              "success": False,
              "message": "Cannot find instance_url in either server_config or auth_manager",
          }
      
      # Get the headers
      headers = _get_headers(auth_manager, server_config)
      if not headers:
          return {
              "success": False,
              "message": "Cannot find get_headers method in either auth_manager or server_config",
          }
      
      # Add Content-Type header
      headers["Content-Type"] = "application/json"
      
      # Make the API request
      url = f"{instance_url}/api/now/table/change_task"
      
      try:
          response = requests.post(url, json=data, headers=headers)
          response.raise_for_status()
          
          result = response.json()
          
          return {
              "success": True,
              "message": "Change task added successfully",
              "change_task": result["result"],
          }
      except requests.exceptions.RequestException as e:
          logger.error(f"Error adding change task: {e}")
          return {
              "success": False,
              "message": f"Error adding change task: {str(e)}",
          }

• src/servicenow_mcp/tools/change_tools.py:73-82 (schema)

  Pydantic model defining the input parameters for the add_change_task tool, including required change_id and short_description, and optional fields.

  class AddChangeTaskParams(BaseModel):
      """Parameters for adding a task to a change request."""
  
      change_id: str = Field(..., description="Change request ID or sys_id")
      short_description: str = Field(..., description="Short description of the task")
      description: Optional[str] = Field(None, description="Detailed description of the task")
      assigned_to: Optional[str] = Field(None, description="User assigned to the task")
      planned_start_date: Optional[str] = Field(None, description="Planned start date (YYYY-MM-DD HH:MM:SS)")
      planned_end_date: Optional[str] = Field(None, description="Planned end date (YYYY-MM-DD HH:MM:SS)")

• src/servicenow_mcp/utils/tool_utils.py:507-513 (registration)

  Registration of the add_change_task tool in the central tool definitions dictionary used by the MCP server. Maps the tool name to its handler (aliased import), schema, description, and serialization settings.

  "add_change_task": (
      add_change_task_tool,
      AddChangeTaskParams,
      str,  # Expects JSON string
      "Add a task to a change request",
      "json_dict",  # Tool returns Pydantic model
  ),

• src/servicenow_mcp/tools/__init__.py:23-32 (registration)

  Import of add_change_task from change_tools.py into the tools package __init__.py, making it available for re-export and use in tool_utils.py.

  from servicenow_mcp.tools.change_tools import (
      add_change_task,
      approve_change,
      create_change_request,
      get_change_request_details,
      list_change_requests,
      reject_change,
      submit_change_for_approval,
      update_change_request,
  )

• src/servicenow_mcp/tools/change_tools.py:107-159 (helper)

  Helper function used by add_change_task (and other tools) for parameter unwrapping, required field checks, and Pydantic validation.

  def _unwrap_and_validate_params(params: Any, model_class: Type[T], required_fields: List[str] = None) -> Dict[str, Any]:
      """
      Helper function to unwrap and validate parameters.
      
      Args:
          params: The parameters to unwrap and validate.
          model_class: The Pydantic model class to validate against.
          required_fields: List of required field names.
          
      Returns:
          A tuple of (success, result) where result is either the validated parameters or an error message.
      """
      # Handle case where params might be wrapped in another dictionary
      if isinstance(params, dict) and len(params) == 1 and "params" in params and isinstance(params["params"], dict):
          logger.warning("Detected params wrapped in a 'params' key. Unwrapping...")
          params = params["params"]
      
      # Handle case where params might be a Pydantic model object
      if not isinstance(params, dict):
          try:
              # Try to convert to dict if it's a Pydantic model
              logger.warning("Params is not a dictionary. Attempting to convert...")
              params = params.dict() if hasattr(params, "dict") else dict(params)
          except Exception as e:
              logger.error(f"Failed to convert params to dictionary: {e}")
              return {
                  "success": False,
                  "message": f"Invalid parameters format. Expected a dictionary, got {type(params).__name__}",
              }
      
      # Validate required parameters are present
      if required_fields:
          for field in required_fields:
              if field not in params:
                  return {
                      "success": False,
                      "message": f"Missing required parameter '{field}'",
                  }
      
      try:
          # Validate parameters against the model
          validated_params = model_class(**params)
          return {
              "success": True,
              "params": validated_params,
          }
      except Exception as e:
          logger.error(f"Error validating parameters: {e}")
          return {
              "success": False,
              "message": f"Error validating parameters: {str(e)}",
          }