Condition with CEL expression: branching on previous step output
Runs a classifier step first, then uses previous_step_content.contains() to decide the next step.
"""Condition with CEL expression: branching on previous step output.
=================================================================
Runs a classifier step first, then uses previous_step_content.contains()
to decide the next step.
Requirements:
pip install cel-python
"""
from agno.agent import Agent
from agno.models.openai import OpenAIChat
from agno.workflow import CEL_AVAILABLE, Condition, Step, Workflow
# ---------------------------------------------------------------------------
# Setup
# ---------------------------------------------------------------------------
if not CEL_AVAILABLE:
print("CEL is not available. Install with: pip install cel-python")
exit(1)
# ---------------------------------------------------------------------------
# Create Agents
# ---------------------------------------------------------------------------
classifier = Agent(
name="Classifier",
model=OpenAIChat(id="gpt-5.6-luna"),
instructions=(
"Classify the request as either TECHNICAL or GENERAL. "
"Respond with exactly one word: TECHNICAL or GENERAL."
),
markdown=False,
)
technical_agent = Agent(
name="Technical Support",
model=OpenAIChat(id="gpt-5.6-luna"),
instructions="You are a technical support specialist. Provide detailed technical help.",
markdown=True,
)
general_agent = Agent(
name="General Support",
model=OpenAIChat(id="gpt-5.6-luna"),
instructions="You handle general inquiries. Be friendly and helpful.",
markdown=True,
)
# ---------------------------------------------------------------------------
# Create Workflow
# ---------------------------------------------------------------------------
workflow = Workflow(
name="CEL Classify and Route",
steps=[
Step(name="Classify", agent=classifier),
Condition(
name="Route by Classification",
evaluator='previous_step_content.contains("TECHNICAL")',
steps=[
Step(name="Technical Help", agent=technical_agent),
],
else_steps=[
Step(name="General Help", agent=general_agent),
],
),
],
)
# ---------------------------------------------------------------------------
# Run Workflow
# ---------------------------------------------------------------------------
if __name__ == "__main__":
print("--- Technical question ---")
workflow.print_response(
input="My API returns 500 errors when I send POST requests with JSON payloads."
)
print()
print("--- General question ---")
workflow.print_response(input="What are your business hours?")Forward the original question
The classifier emits only a label. Restore the original input inside each branch, after the condition has evaluated that label, so the support agent receives the actual question:
from agno.workflow.step import Step
from agno.workflow.types import StepInput, StepOutput
from cel_previous_step import workflow
def restore_question(step_input: StepInput) -> StepOutput:
return StepOutput(content=step_input.input)
condition = workflow.steps[1]
condition.steps.insert(0, Step(name="Restore Technical Question", executor=restore_question))
condition.else_steps.insert(0, Step(name="Restore General Question", executor=restore_question))
workflow.print_response(input="My API returns 500 errors with JSON payloads.")
workflow.print_response(input="What are your business hours?")Run the Example
Set up your virtual environment
uv venv --python 3.12
source .venv/bin/activateInstall dependencies
uv pip install -U agno cel-python fastapi openaiExport your OpenAI API key
export OPENAI_API_KEY="your_openai_api_key_here"Run the example
Save the source as cel_previous_step.py and the separate runner above, then run:
python run_cel_previous_step.pyFull source: cookbook/04_workflows/07_cel_expressions/condition/cel_previous_step.py