The AWS Systems Manager Runbook Executor skill automates operational procedures through AWS SSM Automation documents and Run Command. It leverages boto3 SSM client methods (start_automation_execution, send_command, get_command_invocation) to execute both AWS-managed runbooks (AWS-RunPatchBaseline, AWS-RestartEC2Instance, AWSSupport-TroubleshootSSH) and custom Automation documents written in YAML with aws:executeScript, aws:runCommand, aws:invokeLambdaFunction, and aws:approve steps. The skill handles parameter resolution from SSM Parameter Store (get_parameter, get_parameters_by_path) including SecureString decryption, manages execution with rate controls (MaxConcurrency, MaxErrors) for fleet-wide operations, and supports cross-account execution through shared documents and assume role configurations. It monitors automation execution status through describe_automation_executions, captures step-level output, and handles failure scenarios with onFailure/onCancel specifications. The executor also supports maintenance window integration via register_task_with_maintenance_window, compliance reporting through list_compliance_items, and State Manager associations for desired state enforcement across EC2 fleets.