Agent host (runtime)
The application that runs the agent loop, manages context, executes tools and enforces limits.
The host is everything around the model: it assembles the prompt, calls the model, parses tool calls, executes them (locally or via MCP servers), enforces step/cost/time limits, handles approvals and records traces. Claude Code, Cursor, the OpenAI Agents SDK and LangGraph are hosts; the model is interchangeable underneath.