> ## Documentation Index
> Fetch the complete documentation index at: https://phidatainc-agui.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Nested Workflow with Loop

> Inner workflow with a `Loop` step that iteratively refines research until a quality threshold is met.

```python theme={null}
from typing import List

from agno.agent import Agent
from agno.models.openai import OpenAIChat
from agno.workflow import Loop
from agno.workflow.step import Step
from agno.workflow.types import StepOutput
from agno.workflow.workflow import Workflow


def is_detailed_enough(outputs: List[StepOutput]) -> bool:
    """End the loop when the output is sufficiently detailed (> 200 chars)."""
    if not outputs:
        return False
    last = outputs[-1]
    return last.content is not None and len(str(last.content)) > 200


# Inner workflow: iterative research
researcher = Agent(
    name="Iterative Researcher",
    model=OpenAIChat(id="gpt-4o-mini"),
    instructions=(
        "You are a researcher. Each iteration, expand on the previous research "
        "with more detail and specifics. Build on what was already written."
    ),
)

inner_workflow = Workflow(
    name="Iterative Research",
    description="Researches a topic in iterative passes until sufficiently detailed",
    steps=[
        Loop(
            name="research_loop",
            steps=[Step(name="research_pass", agent=researcher)],
            end_condition=is_detailed_enough,
            max_iterations=3,
        ),
    ],
)

# Outer workflow
writer = Agent(
    name="Writer",
    model=OpenAIChat(id="gpt-4o-mini"),
    instructions="Write a polished summary from the detailed research provided.",
)

outer_workflow = Workflow(
    name="Iterative Research and Write",
    description="Iteratively researches until detailed, then writes a summary",
    steps=[
        Step(name="research_phase", workflow=inner_workflow),
        Step(name="writing_phase", agent=writer),
    ],
)


if __name__ == "__main__":
    outer_workflow.print_response(
        input="Explain how neural networks learn",
        stream=True,
    )
```

## Run the Example

```bash theme={null}
git clone https://github.com/agno-agi/agno.git
cd agno/cookbook/04_workflows/06_advanced_concepts/workflow_as_a_step

pip install agno openai

python nested_workflow_with_loop.py
```