Rails MCP Tool Pattern: ForbiddenAttributesError Fix When using `params.slice()` in MCP tool handlers, always call `.to_h` to convert `ActionController::Parameters` to plain hash before passing to model methods like `update!`. **Why:** Rails strong parameters protection will raise `ActiveModel::ForbiddenAttributesError` if you pass `ActionController::Parameters` directly without proper permitting. **Correct pattern:** ```ruby update_params = params.slice(:field1, :field2).to_h model.update!(update_params) ``` **Incorrect pattern:** ```ruby update_params = params.slice(:field1, :field2) # Returns ActionController::Parameters model.update!(update_params) # Raises ForbiddenAttributesError ``` **Example fix (ticket #157):** - File: app/controllers/api/v1/mcp_controller.rb:handle_update_ticket - Changed `params.slice(...)` to `params.slice(...).to_h` - Also applies to nested params like `params[:working_memory].to_h`