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Stop an agent run early with StopAgentRun when you need to pause after collecting partial inputs in session state. 

from agno.agent import Agent
from agno.db.sqlite import SqliteDb
from agno.exceptions import StopAgentRun
from agno.models.openai import OpenAIChat
from agno.run import RunContext
from agno.utils.log import logger

# ---------------------------------------------------------------------------
# Create Agent
# ---------------------------------------------------------------------------


def add_item(run_context: RunContext, item: str) -> str:
    """Add an item to the shopping list."""
    if run_context.session_state is None:
        run_context.session_state = {}

    if "shopping_list" not in run_context.session_state:
        run_context.session_state["shopping_list"] = []

    run_context.session_state["shopping_list"].append(item)
    len_shopping_list = len(run_context.session_state["shopping_list"])

    if len_shopping_list < 3:
        raise StopAgentRun(
            f"Shopping list is: {run_context.session_state['shopping_list']}. We must stop the agent."  # type: ignore
        )

    logger.info(
        f"The shopping list is now: {run_context.session_state.get('shopping_list')}"
    )  # type: ignore
    return f"The shopping list is now: {run_context.session_state.get('shopping_list')}"  # type: ignore


agent = Agent(
    model=OpenAIChat(id="gpt-5.2"),
    session_id="stop_agent_exception_session",
    db=SqliteDb(
        session_table="stop_agent_exception_session",
        db_file="tmp/stop_agent_exception.db",
    ),
    # Initialize the session state with empty shopping list
    session_state={"shopping_list": []},
    tools=[add_item],
    markdown=True,
)

# ---------------------------------------------------------------------------
# Run Agent
# ---------------------------------------------------------------------------
if __name__ == "__main__":
    agent.print_response("Add milk", stream=True)
    print(
        f"Final session state: {agent.get_session_state(session_id='stop_agent_exception_session')}"
    )

​
Run the Example

# Clone and setup repo
git clone https://github.com/agno-agi/agno.git
cd agno/cookbook/91_tools/exceptions

# Create and activate virtual environment
./scripts/demo_setup.sh
source .venvs/demo/bin/activate

python stop_agent_exception.py
For details, see Stop Agent cookbook.