# Source: https://docs.crewai.com/en/concepts/crews.md

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.crewai.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Crews

> Understanding and utilizing crews in the crewAI framework with comprehensive attributes and functionalities.

## Overview

A crew in crewAI represents a collaborative group of agents working together to achieve a set of tasks. Each crew defines the strategy for task execution, agent collaboration, and the overall workflow.

## Crew Attributes

| Attribute                             | Parameters             | Description                                                                                                                                                                                           |   |
| :------------------------------------ | :--------------------- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | - |
| **Tasks**                             | `tasks`                | A list of tasks assigned to the crew.                                                                                                                                                                 |   |
| **Agents**                            | `agents`               | A list of agents that are part of the crew.                                                                                                                                                           |   |
| **Process** *(optional)*              | `process`              | The process flow (e.g., sequential, hierarchical) the crew follows. Default is `sequential`.                                                                                                          |   |
| **Verbose** *(optional)*              | `verbose`              | The verbosity level for logging during execution. Defaults to `False`.                                                                                                                                |   |
| **Manager LLM** *(optional)*          | `manager_llm`          | The language model used by the manager agent in a hierarchical process. **Required when using a hierarchical process.**                                                                               |   |
| **Function Calling LLM** *(optional)* | `function_calling_llm` | If passed, the crew will use this LLM to do function calling for tools for all agents in the crew. Each agent can have its own LLM, which overrides the crew's LLM for function calling.              |   |
| **Config** *(optional)*               | `config`               | Optional configuration settings for the crew, in `Json` or `Dict[str, Any]` format.                                                                                                                   |   |
| **Max RPM** *(optional)*              | `max_rpm`              | Maximum requests per minute the crew adheres to during execution. Defaults to `None`.                                                                                                                 |   |
| **Memory** *(optional)*               | `memory`               | Utilized for storing execution memories (short-term, long-term, entity memory).                                                                                                                       |   |
| **Cache** *(optional)*                | `cache`                | Specifies whether to use a cache for storing the results of tools' execution. Defaults to `True`.                                                                                                     |   |
| **Embedder** *(optional)*             | `embedder`             | Configuration for the embedder to be used by the crew. Mostly used by memory for now. Default is `{"provider": "openai"}`.                                                                            |   |
| **Step Callback** *(optional)*        | `step_callback`        | A function that is called after each step of every agent. This can be used to log the agent's actions or to perform other operations; it won't override the agent-specific `step_callback`.           |   |
| **Task Callback** *(optional)*        | `task_callback`        | A function that is called after the completion of each task. Useful for monitoring or additional operations post-task execution.                                                                      |   |
| **Share Crew** *(optional)*           | `share_crew`           | Whether you want to share the complete crew information and execution with the crewAI team to make the library better, and allow us to train models.                                                  |   |
| **Output Log File** *(optional)*      | `output_log_file`      | Set to True to save logs as logs.txt in the current directory or provide a file path. Logs will be in JSON format if the filename ends in .json, otherwise .txt. Defaults to `None`.                  |   |
| **Manager Agent** *(optional)*        | `manager_agent`        | `manager` sets a custom agent that will be used as a manager.                                                                                                                                         |   |
| **Prompt File** *(optional)*          | `prompt_file`          | Path to the prompt JSON file to be used for the crew.                                                                                                                                                 |   |
| **Planning** *(optional)*             | `planning`             | Adds planning ability to the Crew. When activated before each Crew iteration, all Crew data is sent to an AgentPlanner that will plan the tasks and this plan will be added to each task description. |   |
| **Planning LLM** *(optional)*         | `planning_llm`         | The language model used by the AgentPlanner in a planning process.                                                                                                                                    |   |
| **Knowledge Sources** *(optional)*    | `knowledge_sources`    | Knowledge sources available at the crew level, accessible to all the agents.                                                                                                                          |   |
| **Stream** *(optional)*               | `stream`               | Enable streaming output to receive real-time updates during crew execution. Returns a `CrewStreamingOutput` object that can be iterated for chunks. Defaults to `False`.                              |   |

<Tip>
  **Crew Max RPM**: The `max_rpm` attribute sets the maximum number of requests per minute the crew can perform to avoid rate limits and will override individual agents' `max_rpm` settings if you set it.
</Tip>

## Creating Crews

There are two ways to create crews in CrewAI: using **YAML configuration (recommended)** or defining them **directly in code**.

### YAML Configuration (Recommended)

Using YAML configuration provides a cleaner, more maintainable way to define crews and is consistent with how agents and tasks are defined in CrewAI projects.

After creating your CrewAI project as outlined in the [Installation](/en/installation) section, you can define your crew in a class that inherits from `CrewBase` and uses decorators to define agents, tasks, and the crew itself.

#### Example Crew Class with Decorators

```python code theme={null}
from crewai import Agent, Crew, Task, Process
from crewai.project import CrewBase, agent, task, crew, before_kickoff, after_kickoff
from crewai.agents.agent_builder.base_agent import BaseAgent
from typing import List

@CrewBase
class YourCrewName:
    """Description of your crew"""

    agents: List[BaseAgent]
    tasks: List[Task]

    # Paths to your YAML configuration files
    # To see an example agent and task defined in YAML, checkout the following:
    # - Task: https://docs.crewai.com/concepts/tasks#yaml-configuration-recommended
    # - Agents: https://docs.crewai.com/concepts/agents#yaml-configuration-recommended
    agents_config = 'config/agents.yaml'
    tasks_config = 'config/tasks.yaml'

    @before_kickoff
    def prepare_inputs(self, inputs):
        # Modify inputs before the crew starts
        inputs['additional_data'] = "Some extra information"
        return inputs

    @after_kickoff
    def process_output(self, output):
        # Modify output after the crew finishes
        output.raw += "\nProcessed after kickoff."
        return output

    @agent
    def agent_one(self) -> Agent:
        return Agent(
            config=self.agents_config['agent_one'], # type: ignore[index]
            verbose=True
        )

    @agent
    def agent_two(self) -> Agent:
        return Agent(
            config=self.agents_config['agent_two'], # type: ignore[index]
            verbose=True
        )

    @task
    def task_one(self) -> Task:
        return Task(
            config=self.tasks_config['task_one'] # type: ignore[index]
        )

    @task
    def task_two(self) -> Task:
        return Task(
            config=self.tasks_config['task_two'] # type: ignore[index]
        )

    @crew
    def crew(self) -> Crew:
        return Crew(
            agents=self.agents,  # Automatically collected by the @agent decorator
            tasks=self.tasks,    # Automatically collected by the @task decorator.
            process=Process.sequential,
            verbose=True,
        )
```

How to run the above code:

```python code theme={null}
YourCrewName().crew().kickoff(inputs={"any": "input here"})
```

<Note>
  Tasks will be executed in the order they are defined.
</Note>

The `CrewBase` class, along with these decorators, automates the collection of agents and tasks, reducing the need for manual management.

#### Decorators overview from `annotations.py`

CrewAI provides several decorators in the `annotations.py` file that are used to mark methods within your crew class for special handling:

* `@CrewBase`: Marks the class as a crew base class.
* `@agent`: Denotes a method that returns an `Agent` object.
* `@task`: Denotes a method that returns a `Task` object.
* `@crew`: Denotes the method that returns the `Crew` object.
* `@before_kickoff`: (Optional) Marks a method to be executed before the crew starts.
* `@after_kickoff`: (Optional) Marks a method to be executed after the crew finishes.

These decorators help in organizing your crew's structure and automatically collecting agents and tasks without manually listing them.

### Direct Code Definition (Alternative)

Alternatively, you can define the crew directly in code without using YAML configuration files.

```python code theme={null}
from crewai import Agent, Crew, Task, Process
from crewai_tools import YourCustomTool

class YourCrewName:
    def agent_one(self) -> Agent:
        return Agent(
            role="Data Analyst",
            goal="Analyze data trends in the market",
            backstory="An experienced data analyst with a background in economics",
            verbose=True,
            tools=[YourCustomTool()]
        )

    def agent_two(self) -> Agent:
        return Agent(
            role="Market Researcher",
            goal="Gather information on market dynamics",
            backstory="A diligent researcher with a keen eye for detail",
            verbose=True
        )

    def task_one(self) -> Task:
        return Task(
            description="Collect recent market data and identify trends.",
            expected_output="A report summarizing key trends in the market.",
            agent=self.agent_one()
        )

    def task_two(self) -> Task:
        return Task(
            description="Research factors affecting market dynamics.",
            expected_output="An analysis of factors influencing the market.",
            agent=self.agent_two()
        )

    def crew(self) -> Crew:
        return Crew(
            agents=[self.agent_one(), self.agent_two()],
            tasks=[self.task_one(), self.task_two()],
            process=Process.sequential,
            verbose=True
        )
```

How to run the above code:

```python code theme={null}
YourCrewName().crew().kickoff(inputs={})
```

In this example:

* Agents and tasks are defined directly within the class without decorators.
* We manually create and manage the list of agents and tasks.
* This approach provides more control but can be less maintainable for larger projects.

## Crew Output

The output of a crew in the CrewAI framework is encapsulated within the `CrewOutput` class.
This class provides a structured way to access results of the crew's execution, including various formats such as raw strings, JSON, and Pydantic models.
The `CrewOutput` includes the results from the final task output, token usage, and individual task outputs.

### Crew Output Attributes

| Attribute        | Parameters     | Type                       | Description                                                                                          |
| :--------------- | :------------- | :------------------------- | :--------------------------------------------------------------------------------------------------- |
| **Raw**          | `raw`          | `str`                      | The raw output of the crew. This is the default format for the output.                               |
| **Pydantic**     | `pydantic`     | `Optional[BaseModel]`      | A Pydantic model object representing the structured output of the crew.                              |
| **JSON Dict**    | `json_dict`    | `Optional[Dict[str, Any]]` | A dictionary representing the JSON output of the crew.                                               |
| **Tasks Output** | `tasks_output` | `List[TaskOutput]`         | A list of `TaskOutput` objects, each representing the output of a task in the crew.                  |
| **Token Usage**  | `token_usage`  | `Dict[str, Any]`           | A summary of token usage, providing insights into the language model's performance during execution. |

### Crew Output Methods and Properties

| Method/Property | Description                                                                                       |
| :-------------- | :------------------------------------------------------------------------------------------------ |
| **json**        | Returns the JSON string representation of the crew output if the output format is JSON.           |
| **to\_dict**    | Converts the JSON and Pydantic outputs to a dictionary.                                           |
| \***\*str\*\*** | Returns the string representation of the crew output, prioritizing Pydantic, then JSON, then raw. |

### Accessing Crew Outputs

Once a crew has been executed, its output can be accessed through the `output` attribute of the `Crew` object. The `CrewOutput` class provides various ways to interact with and present this output.

#### Example

```python Code theme={null}
# Example crew execution
crew = Crew(
    agents=[research_agent, writer_agent],
    tasks=[research_task, write_article_task],
    verbose=True
)

crew_output = crew.kickoff()

# Accessing the crew output
print(f"Raw Output: {crew_output.raw}")
if crew_output.json_dict:
    print(f"JSON Output: {json.dumps(crew_output.json_dict, indent=2)}")
if crew_output.pydantic:
    print(f"Pydantic Output: {crew_output.pydantic}")
print(f"Tasks Output: {crew_output.tasks_output}")
print(f"Token Usage: {crew_output.token_usage}")
```

## Accessing Crew Logs

You can see real time log of the crew execution, by setting `output_log_file` as a `True(Boolean)` or a `file_name(str)`. Supports logging of events as both `file_name.txt` and `file_name.json`.
In case of `True(Boolean)` will save as `logs.txt`.

In case of `output_log_file` is set as `False(Boolean)` or `None`, the logs will not be populated.

```python Code theme={null}
# Save crew logs
crew = Crew(output_log_file = True)  # Logs will be saved as logs.txt
crew = Crew(output_log_file = file_name)  # Logs will be saved as file_name.txt
crew = Crew(output_log_file = file_name.txt)  # Logs will be saved as file_name.txt
crew = Crew(output_log_file = file_name.json)  # Logs will be saved as file_name.json
```

## Memory Utilization

Crews can utilize memory (short-term, long-term, and entity memory) to enhance their execution and learning over time. This feature allows crews to store and recall execution memories, aiding in decision-making and task execution strategies.

## Cache Utilization

Caches can be employed to store the results of tools' execution, making the process more efficient by reducing the need to re-execute identical tasks.

## Crew Usage Metrics

After the crew execution, you can access the `usage_metrics` attribute to view the language model (LLM) usage metrics for all tasks executed by the crew. This provides insights into operational efficiency and areas for improvement.

```python Code theme={null}
# Access the crew's usage metrics
crew = Crew(agents=[agent1, agent2], tasks=[task1, task2])
crew.kickoff()
print(crew.usage_metrics)
```

## Crew Execution Process

* **Sequential Process**: Tasks are executed one after another, allowing for a linear flow of work.
* **Hierarchical Process**: A manager agent coordinates the crew, delegating tasks and validating outcomes before proceeding. **Note**: A `manager_llm` or `manager_agent` is required for this process and it's essential for validating the process flow.

### Kicking Off a Crew

Once your crew is assembled, initiate the workflow with the `kickoff()` method. This starts the execution process according to the defined process flow.

```python Code theme={null}
# Start the crew's task execution
result = my_crew.kickoff()
print(result)
```

### Different Ways to Kick Off a Crew

Once your crew is assembled, initiate the workflow with the appropriate kickoff method. CrewAI provides several methods for better control over the kickoff process.

#### Synchronous Methods

* `kickoff()`: Starts the execution process according to the defined process flow.
* `kickoff_for_each()`: Executes tasks sequentially for each provided input event or item in the collection.

#### Asynchronous Methods

CrewAI offers two approaches for async execution:

| Method                     | Type         | Description                                            |
| -------------------------- | ------------ | ------------------------------------------------------ |
| `akickoff()`               | Native async | True async/await throughout the entire execution chain |
| `akickoff_for_each()`      | Native async | Native async execution for each input in a list        |
| `kickoff_async()`          | Thread-based | Wraps synchronous execution in `asyncio.to_thread`     |
| `kickoff_for_each_async()` | Thread-based | Thread-based async for each input in a list            |

<Note>
  For high-concurrency workloads, `akickoff()` and `akickoff_for_each()` are recommended as they use native async for task execution, memory operations, and knowledge retrieval.
</Note>

```python Code theme={null}
# Start the crew's task execution
result = my_crew.kickoff()
print(result)

# Example of using kickoff_for_each
inputs_array = [{'topic': 'AI in healthcare'}, {'topic': 'AI in finance'}]
results = my_crew.kickoff_for_each(inputs=inputs_array)
for result in results:
    print(result)

# Example of using native async with akickoff
inputs = {'topic': 'AI in healthcare'}
async_result = await my_crew.akickoff(inputs=inputs)
print(async_result)

# Example of using native async with akickoff_for_each
inputs_array = [{'topic': 'AI in healthcare'}, {'topic': 'AI in finance'}]
async_results = await my_crew.akickoff_for_each(inputs=inputs_array)
for async_result in async_results:
    print(async_result)

# Example of using thread-based kickoff_async
inputs = {'topic': 'AI in healthcare'}
async_result = await my_crew.kickoff_async(inputs=inputs)
print(async_result)

# Example of using thread-based kickoff_for_each_async
inputs_array = [{'topic': 'AI in healthcare'}, {'topic': 'AI in finance'}]
async_results = await my_crew.kickoff_for_each_async(inputs=inputs_array)
for async_result in async_results:
    print(async_result)
```

These methods provide flexibility in how you manage and execute tasks within your crew, allowing for both synchronous and asynchronous workflows tailored to your needs. For detailed async examples, see the [Kickoff Crew Asynchronously](/en/learn/kickoff-async) guide.

### Streaming Crew Execution

For real-time visibility into crew execution, you can enable streaming to receive output as it's generated:

```python Code theme={null}
# Enable streaming
crew = Crew(
    agents=[researcher],
    tasks=[task],
    stream=True
)

# Iterate over streaming output
streaming = crew.kickoff(inputs={"topic": "AI"})
for chunk in streaming:
    print(chunk.content, end="", flush=True)

# Access final result
result = streaming.result
```

Learn more about streaming in the [Streaming Crew Execution](/en/learn/streaming-crew-execution) guide.

### Replaying from a Specific Task

You can now replay from a specific task using our CLI command `replay`.

The replay feature in CrewAI allows you to replay from a specific task using the command-line interface (CLI). By running the command `crewai replay -t <task_id>`, you can specify the `task_id` for the replay process.

Kickoffs will now save the latest kickoffs returned task outputs locally for you to be able to replay from.

### Replaying from a Specific Task Using the CLI

To use the replay feature, follow these steps:

1. Open your terminal or command prompt.
2. Navigate to the directory where your CrewAI project is located.
3. Run the following command:

To view the latest kickoff task IDs, use:

```shell  theme={null}
crewai log-tasks-outputs
```

Then, to replay from a specific task, use:

```shell  theme={null}
crewai replay -t <task_id>
```

These commands let you replay from your latest kickoff tasks, still retaining context from previously executed tasks.