CrewAI

CrewAI has two orchestration layers. A Crew is a set of agents, each described by a role, goal and backstory, and a list of tasks. The crew's process decides who does what: sequential runs tasks in list order and passes earlier outputs as context, while hierarchical adds a manager (an LLM or a custom agent) that allocates tasks, checks results and decides when the work is done. Agents may also be allowed to delegate to one another.

A Flow is the deterministic layer: a class whose methods are wired with @start, @listen and @router decorators, sharing a typed or unstructured state object. Flows can call crews, single agents or plain Python, and the docs recommend them as the structure for production apps.

State and memory: Flow state can be persisted and restored, checkpointing records execution snapshots for resume and fork, and the unified Memory class stores facts that crews, agents or flows can recall later. New projects from crewai create crew are JSON-first (agents/*.jsonc, crew.jsonc); a --classic flag keeps the older Python/YAML layout.

Three documented mechanisms. (1) Setting human_input=True on a task makes the agent ask the user for input in the console before it returns its final answer. (2) In Flows, the @human_feedback decorator (CrewAI 1.8.0+) pauses after a method, shows the output for review, and can map free-text feedback to outcomes such as approved or rejected that route to different listeners; it blocks on console input by default, and a custom HumanFeedbackProvider makes it non-blocking (for example a webhook or Slack callback). (3) Webhook-based human input with a resume API is documented for the Enterprise (AMP) platform. The AG-UI frontend guides also show pausing a run for a user decision in a CopilotKit UI.

uv tool install crewai

from crewai import Agent, Task, Crew, Process

researcher = Agent(role="Researcher", goal="Collect facts about {topic}",
                   backstory="You check primary sources.", llm="gpt-4o-mini")
writer = Agent(role="Writer", goal="Turn notes into a short brief",
               backstory="You write plain summaries.", llm="gpt-4o-mini")

notes = Task(description="List five facts about {topic}.",
             expected_output="Five bullet points", agent=researcher)
brief = Task(description="Write a 100-word brief from the notes.",
             expected_output="One paragraph", agent=writer,
             context=[notes], human_input=True)  # asks you before finishing

crew = Crew(agents=[researcher, writer], tasks=[notes, brief],
            process=Process.sequential)
result = crew.kickoff(inputs={"topic": "the A2A protocol"})
print(result.raw)

• Requires Python >=3.10 and <3.14.
• uv tool install crewai installs the CLI; inside a project use crewai install or add crewai to the project environment, since upgrading the CLI does not upgrade a project's pinned version.
• On Windows, a chroma-hnswlib build error means Visual Studio Build Tools (C++ workload) are missing.
• Agents default to OpenAI models, so OPENAI_API_KEY must be set unless another LLM is configured.
• crewai create crew now generates a JSON-first project; pass --classic for the older crew.py + YAML layout.
• Anonymous telemetry is on by default; set OTEL_SDK_DISABLED=true to turn it off.

Yes, as a client. Agents can load tools from MCP servers through the mcps field or MCPServerAdapter, over stdio, SSE or Streamable HTTP.

Yes. With the crewai[a2a] extra, an agent can delegate to remote A2A agents (A2AClientConfig) or be exposed as an A2A server (A2AServerConfig).

The framework is MIT-licensed. crewAI, Inc. also sells CrewAI AMP; its pricing page lists a free Basic tier and a custom-priced Enterprise plan.

CrewAI publishes an official skills pack (crewaiinc/skills, also a Claude Code plugin) that teaches coding agents such as Claude Code and Codex how to write CrewAI projects. It is guidance for the coding agent, not a runtime integration.

A Crew lets role-based agents work through tasks, sequentially or under a manager. A Flow is an event-driven class with explicit steps and shared state that can call crews.