CrewAI

Description

CrewAI is the MIT-licensed Python framework from CrewAI Inc. that models a multi-agent system as a Crew: a collaborative group of role-defined Agent objects assigned ordered Task objects and executed under a declared Process (sequential by default, or hierarchical with a manager agent). On top of crews, CrewAI exposes Flows, an event-driven orchestration layer built around @start, @listen, and @router decorators that manages typed state and routes execution based on emitted events. The framework ships a unified memory store (LanceDB by default at ./.crewai/memory), automatic delegation/ask-question collaboration tools, MCP integration via the mcps field and MCPServerAdapter, and structured outputs via Pydantic.

Solution

Crew/Process loop: a Crew binds Agents to ordered Tasks and runs them under Process.sequential (linear chaining, each task feeds the next) or Process.hierarchical (a manager_llm delegates to crew members and validates outcomes). Flows wrap Crews in an event-driven graph where @start() methods are entry points, @listen(other_method) fires when its upstream emits, and @router() emits labels that other listeners gate on. Per-agent budgets (max_iter default 25, max_rpm, max_execution_time) bound the inner ReAct/tool loop.

Primary use cases

• teams of role-playing agents collaborating on a project
• event-driven multi-step workflows that mix LLM calls and code
• hierarchical workflows with a manager agent delegating to specialists