This engine parses declarative YAML workflows describing agent graphs, resolving dependencies and executing them by making LLM calls, running scripts, querying databases, and calling MCP tools. It supports streaming, tool calling, and structured output across OpenAI, Anthropic, Gemini, DeepSeek, and other providers. The harness layer injects workflow-level instructions into generate nodes, and built-in data connectors bridge to PostgreSQL, MySQL, MongoDB, Redis, Qdrant, S3, and REST APIs.