ServiceNow MCP Server

Instructions

Implementation Reference

• src/servicenow_mcp/tools/change_tools.py:502-581 (handler)

  The main handler function that executes the tool logic: validates input params, fetches change request details and associated tasks via ServiceNow REST API.

  def get_change_request_details(
      auth_manager: AuthManager,
      server_config: ServerConfig,
      params: Dict[str, Any],
  ) -> Dict[str, Any]:
      """
      Get details of a change request from ServiceNow.
  
      Args:
          auth_manager: The authentication manager.
          server_config: The server configuration.
          params: The parameters for getting change request details.
  
      Returns:
          The change request details.
      """
      # Unwrap and validate parameters
      result = _unwrap_and_validate_params(
          params, 
          GetChangeRequestDetailsParams,
          required_fields=["change_id"]
      )
      
      if not result["success"]:
          return result
      
      validated_params = result["params"]
      
      # 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",
          }
      
      # Make the API request
      url = f"{instance_url}/api/now/table/change_request/{validated_params.change_id}"
      
      params = {
          "sysparm_display_value": "true",
      }
      
      try:
          response = requests.get(url, headers=headers, params=params)
          response.raise_for_status()
          
          result = response.json()
          
          # Get tasks associated with this change request
          tasks_url = f"{instance_url}/api/now/table/change_task"
          tasks_params = {
              "sysparm_query": f"change_request={validated_params.change_id}",
              "sysparm_display_value": "true",
          }
          
          tasks_response = requests.get(tasks_url, headers=headers, params=tasks_params)
          tasks_response.raise_for_status()
          
          tasks_result = tasks_response.json()
          
          return {
              "success": True,
              "change_request": result["result"],
              "tasks": tasks_result["result"],
          }
      except requests.exceptions.RequestException as e:
          logger.error(f"Error getting change request details: {e}")
          return {
              "success": False,
              "message": f"Error getting change request details: {str(e)}",
          }

• src/servicenow_mcp/tools/change_tools.py:67-71 (schema)

  Pydantic BaseModel defining the input schema for the tool, requiring a 'change_id' field.

  class GetChangeRequestDetailsParams(BaseModel):
      """Parameters for getting change request details."""
  
      change_id: str = Field(..., description="Change request ID or sys_id")

• src/servicenow_mcp/utils/tool_utils.py:511-517 (registration)

  Registration of the tool in the central tool_definitions dictionary used by the MCP server to expose the tool.

  "get_change_request_details": (
      get_change_request_details_tool,
      GetChangeRequestDetailsParams,
      str,  # Expects JSON string
      "Get detailed information about a specific change request",
      "json",  # Tool returns list/dict
  ),

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

  Shared helper function used by multiple tools (including this one) to unwrap, validate input parameters against Pydantic models, and handle common formatting issues.

  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)}",
          }