ServiceNow MCP Server

Instructions

Implementation Reference

• src/servicenow_mcp/tools/change_tools.py:302-394 (handler)

  The main handler function for the update_change_request tool. It validates input parameters using Pydantic, prepares the update data, constructs the ServiceNow API URL, and performs a PUT request to update the change request.

  def update_change_request(
      auth_manager: AuthManager,
      server_config: ServerConfig,
      params: Dict[str, Any],
  ) -> Dict[str, Any]:
      """
      Update an existing change request in ServiceNow.
  
      Args:
          auth_manager: The authentication manager.
          server_config: The server configuration.
          params: The parameters for updating the change request.
  
      Returns:
          The updated change request.
      """
      # Unwrap and validate parameters
      result = _unwrap_and_validate_params(
          params, 
          UpdateChangeRequestParams, 
          required_fields=["change_id"]
      )
      
      if not result["success"]:
          return result
      
      validated_params = result["params"]
      
      # Prepare the request data
      data = {}
      
      # Add fields if provided
      if validated_params.short_description:
          data["short_description"] = validated_params.short_description
      if validated_params.description:
          data["description"] = validated_params.description
      if validated_params.state:
          data["state"] = validated_params.state
      if validated_params.risk:
          data["risk"] = validated_params.risk
      if validated_params.impact:
          data["impact"] = validated_params.impact
      if validated_params.category:
          data["category"] = validated_params.category
      if validated_params.assignment_group:
          data["assignment_group"] = validated_params.assignment_group
      if validated_params.start_date:
          data["start_date"] = validated_params.start_date
      if validated_params.end_date:
          data["end_date"] = validated_params.end_date
      if validated_params.work_notes:
          data["work_notes"] = validated_params.work_notes
      
      # 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_request/{validated_params.change_id}"
      
      try:
          response = requests.put(url, json=data, headers=headers)
          response.raise_for_status()
          
          result = response.json()
          
          return {
              "success": True,
              "message": "Change request updated successfully",
              "change_request": result["result"],
          }
      except requests.exceptions.RequestException as e:
          logger.error(f"Error updating change request: {e}")
          return {
              "success": False,
              "message": f"Error updating change request: {str(e)}",
          }

• src/servicenow_mcp/tools/change_tools.py:38-52 (schema)

  Pydantic BaseModel defining the input schema for the update_change_request tool, including required change_id and optional fields for updating the change request.

  class UpdateChangeRequestParams(BaseModel):
      """Parameters for updating a change request."""
  
      change_id: str = Field(..., description="Change request ID or sys_id")
      short_description: Optional[str] = Field(None, description="Short description of the change request")
      description: Optional[str] = Field(None, description="Detailed description of the change request")
      state: Optional[str] = Field(None, description="State of the change request")
      risk: Optional[str] = Field(None, description="Risk level of the change")
      impact: Optional[str] = Field(None, description="Impact of the change")
      category: Optional[str] = Field(None, description="Category of the change")
      assignment_group: Optional[str] = Field(None, description="Group assigned to the change")
      start_date: Optional[str] = Field(None, description="Planned start date (YYYY-MM-DD HH:MM:SS)")
      end_date: Optional[str] = Field(None, description="Planned end date (YYYY-MM-DD HH:MM:SS)")
      work_notes: Optional[str] = Field(None, description="Work notes to add to the change request")

• src/servicenow_mcp/utils/tool_utils.py:440-446 (registration)

  Registration of the update_change_request tool in the central tool_definitions dictionary used by the MCP server, mapping the tool name to its handler function, input schema, return type, description, and serialization method.

  "update_change_request": (
      update_change_request_tool,
      UpdateChangeRequestParams,
      str,
      "Update an existing change request in ServiceNow",
      "str",
  ),

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

  Shared helper function used by the handler (and other tools) to unwrap, validate required fields, and parse input parameters against the Pydantic schema.

  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)}",
          }