Agents are the intelligent, autonomous entities that power your AI workflows in ControlFlow. They represent AI models capable of understanding instructions, making decisions, and completing tasks. 
import controlflow as cf

agent = cf.Agent("Marvin")

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What are agents?

Agents in ControlFlow are configurable AI entities, each with its own identity, capabilities, and even personality. They act as the “workers” in your AI workflows, responsible for executing tasks and making decisions based on their assigned objectives and available tools. You can think of each agent as a portable LLM configuration. When you assign one or more agents to a task, they will collaborate to complete the task according to the instructions and tools you provide.

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Creating agents

To create an agent, use the Agent class. 
import controlflow as cf

agent = cf.Agent(name="Marvin")
A more complex agent can be created by providing additional configuration. This agent shows almost every possible configuration option: 
import controlflow as cf

agent = cf.Agent(
    name="Data Analyst",
    description="An AI agent specialized in data analysis",
    instructions=(
        "Perform data analysis tasks efficiently and accurately. "
        "Browse the web for data and use Python to analyze it."
    ),
    tools=[cf.tools.web.get_url, cf.tools.code.python],
    model="openai/gpt-4o",
    interactive=True,
)

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Agent properties

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Name

An agent’s name is an identifier that is visible to other agents in the workflow. It is used to distinguish between agents and for logging and debugging purposes. If possible, keep agent names unique within a flow to avoid confusion. While agents do have deterministic IDs that can be used to disambiguate two agents with the same name, they will often use names when interacting with each other.

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Description

A description is a brief summary of the agent’s role or specialization. This information is visible to other agents, and helps them understand the agent’s capabilities and expertise.

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Instructions

Instructions are specific instructions or guidelines for the agent to follow during task execution. These instructions are private and not shared with other agents.

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Tools

Tools are Python functions that the agent can call to perform specific actions or computations. They are defined as a list of functions when creating an agent, and can be used to enhance the agent’s capabilities. The agent will have access to these tools in every task they are assigned to. If a task defines additional tools, the agent will have access to those as well.

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Model

Each agent has a model, which is the LLM that powers the agent responses. This allows you to choose the most suitable model for your needs, based on factors such as performance, latency, and cost. ControlFlow supports any LangChain LLM that supports chat and function calling. For more details on how to configure models, see the LLMs guide. 
import controlflow as cf


agent1 = cf.Agent(model="openai/gpt-4o")
agent2 = cf.Agent(model="anthropic/claude-3-5-sonnet-20240620")

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LLM rules

New in version 0.11.0 Each LLM provider may have different requirements for how messages are formatted or presented. For example, OpenAI permits system messages to be interspersed between user messages, but Anthropic requires them to be at the beginning of the conversation. ControlFlow uses provider-specific rules to properly compile messages for each agent’s API. For common providers like OpenAI and Anthropic, LLM rules can be automatically inferred from the agent’s model. However, you can use a custom LLMRules object to override these rules or provide rules for non-standard providers. Here is an example of how to tell the agent to use the Anthropic compilation rules with a custom model that can’t be automatically inferred: 
import controlflow as cf

# note: this is just an example
llm_model = CustomAnthropicModel()

agent = cf.Agent(
    model=model,
    llm_rules=cf.llm.rules.AnthropicRules(model=model)
)

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Interactivity

By default, agents have no way to communicate with users. If you want to chat with an agent, set interactive=True. By default, this will let the agent communicate with users on the command line. To learn more, see the Interactivity guide.

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Assigning agents to tasks

Agents must be assigned to tasks in order to work on them. You can assign agents by passing them to the agents parameter when creating a task. Each task requires at least one assigned agent, and will use a default agent if none are provided. Agents can be assigned to multiple tasks, and tasks can have multiple agents.

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Tasks with no agents

If you do not assign any agents to a task, it will determine its agents at runtime according to the following rules:
  1. If the task has a parent, it will use the parent’s agents.
  2. If the task’s flow has a default agent, it will use that agent.
  3. It will use the global default agent (controlflow.defaults.agent).
To see the agents assigned to a task, use its get_agents() method. This will return a list of all the agents assigned to the task, including any inherited from its environment.

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Tasks with one agent

To assign a single agent to a task, pass a agent to the agents parameter:
Providing agents to a task
import controlflow as cf

poet = cf.Agent(name="Poet")

poem = cf.run("Write a short poem about AI", agents=[poet])
Alternatively, you can use the agent’s own run method to create and run a task in one step:
Calling Agent.run()
import controlflow as cf

poet = cf.Agent(name="Poet")

poem = poet.run("Write a short poem about AI")
These two approaches are functionally equivalent.

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Tasks with multiple agents

Assign multiple agents to a task by passing them to the task’s agents parameter as a list. Here, we create two agents and assign them to a task that has them debate each other. 
import controlflow as cf

optimist = cf.Agent(
    name="Optimist",
    instructions="Always find the best in every situation.",
)

pessimist = cf.Agent(
    name="Pessimist",
    instructions="Always find the worst in every situation.",
)

cf.run(
    "Debate world peace",
    agents=[optimist, pessimist],
    instructions=(
        "Mark the task successful once both agents have "
        "found something to agree on."
    )
)
When tasks have multiple agents, it’s important to understand how they collaborate (and to provide them with clear instructions to guide that behavior). To learn more, see the multi-agent collaboration docs.

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Assigning completion agents

By default, every agent assigned to a task will be given tools for marking the task as successful or failed. If you want to restrict completion tools to a specific agent or agents, you can do so by setting the task’s completion_agents.
Setting completion_agents will prevent other agents from marking the task as successful or failed. Make sure your completion agents are also assigned to the task!
Completion agents
import controlflow as cf

a1 = cf.Agent(name="A1")
a2 = cf.Agent(name="A2")
a3 = cf.Agent(name="A3")


task = cf.Task(
    ...,
    # all three agents can work on the task
    agents=[a1, a2, a3],
    # only a1 and a2 can mark the task as successful
    completion_agents=[a1, a2],
)