Human-in-the-loop

Learn how to configure human approval for sensitive tool operations

Some tool operations may be sensitive and require human approval before execution. Deep agents support human-in-the-loop workflows through LangGraph’s interrupt capabilities. You can configure which tools require approval using the interrupt_on parameter.

Basic configuration

The interrupt_on parameter accepts a dictionary mapping tool names to interrupt configurations. Each tool can be configured with:

• True: Enable interrupts with default behavior (approve, edit, reject allowed)
• False: Disable interrupts for this tool
• {"allowed_decisions": [...]}: Custom configuration with specific allowed decisions

from langchain.tools import tool
from deepagents import create_deep_agent
from langgraph.checkpoint.memory import MemorySaver

@tool
def delete_file(path: str) -> str:
    """Delete a file from the filesystem."""
    return f"Deleted {path}"

@tool
def read_file(path: str) -> str:
    """Read a file from the filesystem."""
    return f"Contents of {path}"

@tool
def send_email(to: str, subject: str, body: str) -> str:
    """Send an email."""
    return f"Sent email to {to}"

# Checkpointer is REQUIRED for human-in-the-loop
checkpointer = MemorySaver()

agent = create_deep_agent(
    model="claude-sonnet-4-6",
    tools=[delete_file, read_file, send_email],
    interrupt_on={
        "delete_file": True,  # Default: approve, edit, reject
        "read_file": False,   # No interrupts needed
        "send_email": {"allowed_decisions": ["approve", "reject"]},  # No editing
    },
    checkpointer=checkpointer  # Required!
)

Decision types

The allowed_decisions list controls what actions a human can take when reviewing a tool call:

• "approve": Execute the tool with the original arguments as proposed by the agent
• "edit": Modify the tool arguments before execution
• "reject": Skip executing this tool call entirely

You can customize which decisions are available for each tool:

interrupt_on = {
    # Sensitive operations: allow all options
    "delete_file": {"allowed_decisions": ["approve", "edit", "reject"]},

    # Moderate risk: approval or rejection only
    "write_file": {"allowed_decisions": ["approve", "reject"]},

    # Must approve (no rejection allowed)
    "critical_operation": {"allowed_decisions": ["approve"]},
}

Handle interrupts

When an interrupt is triggered, the agent pauses execution and returns control. Check for interrupts in the result and handle them accordingly.

import uuid
from langgraph.types import Command

# Create config with thread_id for state persistence
config = {"configurable": {"thread_id": str(uuid.uuid4())}}

# Invoke the agent
result = agent.invoke({
    "messages": [{"role": "user", "content": "Delete the file temp.txt"}]
}, config=config)

# Check if execution was interrupted
if result.get("__interrupt__"):
    # Extract interrupt information
    interrupts = result["__interrupt__"][0].value
    action_requests = interrupts["action_requests"]
    review_configs = interrupts["review_configs"]

    # Create a lookup map from tool name to review config
    config_map = {cfg["action_name"]: cfg for cfg in review_configs}

    # Display the pending actions to the user
    for action in action_requests:
        review_config = config_map[action["name"]]
        print(f"Tool: {action['name']}")
        print(f"Arguments: {action['args']}")
        print(f"Allowed decisions: {review_config['allowed_decisions']}")

    # Get user decisions (one per action_request, in order)
    decisions = [
        {"type": "approve"}  # User approved the deletion
    ]

    # Resume execution with decisions
    result = agent.invoke(
        Command(resume={"decisions": decisions}),
        config=config  # Must use the same config!
    )

# Process final result
print(result["messages"][-1].content)

Multiple tool calls

When the agent calls multiple tools that require approval, all interrupts are batched together in a single interrupt. You must provide decisions for each one in order.

config = {"configurable": {"thread_id": str(uuid.uuid4())}}

result = agent.invoke({
    "messages": [{
        "role": "user",
        "content": "Delete temp.txt and send an email to [e-mail]"
    }]
}, config=config)

if result.get("__interrupt__"):
    interrupts = result["__interrupt__"][0].value
    action_requests = interrupts["action_requests"]

    # Two tools need approval
    assert len(action_requests) == 2

    # Provide decisions in the same order as action_requests
    decisions = [
        {"type": "approve"},  # First tool: delete_file
        {"type": "reject"}    # Second tool: send_email
    ]

    result = agent.invoke(
        Command(resume={"decisions": decisions}),
        config=config
    )

Edit tool arguments

When "edit" is in the allowed decisions, you can modify the tool arguments before execution:

if result.get("__interrupt__"):
    interrupts = result["__interrupt__"][0].value
    action_request = interrupts["action_requests"][0]

    # Original args from the agent
    print(action_request["args"])  # {"to": "[e-mail]", ...}

    # User decides to edit the recipient
    decisions = [{
        "type": "edit",
        "edited_action": {
            "name": action_request["name"],  # Must include the tool name
            "args": {"to": "[e-mail]", "subject": "...", "body": "..."}
        }
    }]

    result = agent.invoke(
        Command(resume={"decisions": decisions}),
        config=config
    )

Subagent interrupts

When using subagents, you can use interrupts on tool calls and within tool calls.

Interrupts on tool calls

Each subagent can have its own interrupt_on configuration that overrides the main agent’s settings:

agent = create_deep_agent(
    tools=[delete_file, read_file],
    interrupt_on={
        "delete_file": True,
        "read_file": False,
    },
    subagents=[{
        "name": "file-manager",
        "description": "Manages file operations",
        "system_prompt": "You are a file management assistant.",
        "tools": [delete_file, read_file],
        "interrupt_on": {
            # Override: require approval for reads in this subagent
            "delete_file": True,
            "read_file": True,  # Different from main agent!
        }
    }],
    checkpointer=checkpointer
)

When a subagent triggers an interrupt, the handling is the same – check for __interrupt__ and resume with Command.

Interrupts within tool calls

Subagent tools can call interrupt() directly to pause execution and await approval:

from langchain.agents import create_agent
from langchain_anthropic import ChatAnthropic
from langchain.messages import HumanMessage
from langchain.tools import tool
from langgraph.checkpoint.memory import InMemorySaver
from langgraph.types import Command, interrupt

from deepagents.graph import create_deep_agent
from deepagents.middleware.subagents import CompiledSubAgent


@tool(description="Request human approval before proceeding with an action.")
def request_approval(action_description: str) -> str:
    """Request human approval using the interrupt() primitive."""
    # interrupt() pauses execution and returns the value passed to Command(resume=...)
    approval = interrupt({
        "type": "approval_request",
        "action": action_description,
        "message": f"Please approve or reject: {action_description}",
    })

    if approval.get("approved"):
        return f"Action '{action_description}' was APPROVED. Proceeding..."
    else:
        return f"Action '{action_description}' was REJECTED. Reason: {approval.get('reason', 'No reason provided')}"


def main():
    checkpointer = InMemorySaver()
    model = ChatAnthropic(
        model_name="claude-sonnet-4-6",
        max_tokens=4096,
    )

    compiled_subagent = create_agent(
        model=model,
        tools=[request_approval],
        name="approval-agent",
    )

    parent_agent = create_deep_agent(
        checkpointer=checkpointer,
        subagents=[
            CompiledSubAgent(
                name="approval-agent",
                description="An agent that can request approvals",
                runnable=compiled_subagent,
            )
        ],
    )

    thread_id = "test_interrupt_directly"
    config = {"configurable": {"thread_id": thread_id}}

    print("Invoking agent - sub-agent will use request_approval tool...")

    result = parent_agent.invoke(
        {
            "messages": [
                HumanMessage(
                    content="Use the task tool to launch the approval-agent sub-agent. "
                    "Tell it to use the request_approval tool to request approval for 'deploying to production'."
                )
            ]
        },
        config=config,
    )

    # Check for interrupt
    if result.get("__interrupt__"):
        interrupt_value = result["__interrupt__"][0].value
        print(f"\nInterrupt received!")
        print(f"  Type: {interrupt_value.get('type')}")
        print(f"  Action: {interrupt_value.get('action')}")
        print(f"  Message: {interrupt_value.get('message')}")

        print("\nResuming with Command(resume={'approved': True})...")
        result2 = parent_agent.invoke(
            Command(resume={"approved": True}),
            config=config,
        )

        if "__interrupt__" not in result2:
            print("\nExecution completed!")
            # Find the tool response
            tool_msgs = [m for m in result2.get("messages", []) if m.type == "tool"]
            if tool_msgs:
                print(f"  Tool result: {tool_msgs[-1].content}")
        else:
            print("\nAnother interrupt occurred")
    else:
        print("\n  No interrupt - the model may not have called request_approval")


if __name__ == "__main__":
    main()

When run, this produces the following output:

Invoking agent - sub-agent will use request_approval tool...

Interrupt received!
  Type: approval_request
  Action: deploying to production
  Message: Please approve or reject: deploying to production

Resuming with Command(resume={'approved': True})...

Execution completed!
  Tool result: Great! The approval request has been processed. The action **"deploying to production"** was **APPROVED**. You can now proceed with the production deployment.

Best practices

Always use a checkpointer

Human-in-the-loop requires a checkpointer to persist agent state between the interrupt and resume:

from langgraph.checkpoint.memory import MemorySaver

checkpointer = MemorySaver()
agent = create_deep_agent(
    tools=[...],
    interrupt_on={...},
    checkpointer=checkpointer  # Required for HITL
)

Use the same thread ID

When resuming, you must use the same config with the same thread_id:

# First call
config = {"configurable": {"thread_id": "my-thread"}}
result = agent.invoke(input, config=config)

# Resume (use same config)
result = agent.invoke(Command(resume={...}), config=config)

Match decision order to actions

The decisions list must match the order of action_requests:

if result.get("__interrupt__"):
    interrupts = result["__interrupt__"][0].value
    action_requests = interrupts["action_requests"]

    # Create one decision per action, in order
    decisions = []
    for action in action_requests:
        decision = get_user_decision(action)  # Your logic
        decisions.append(decision)

    result = agent.invoke(
        Command(resume={"decisions": decisions}),
        config=config
    )

Tailor configurations by risk

Configure different tools based on their risk level:

interrupt_on = {
    # High risk: full control (approve, edit, reject)
    "delete_file": {"allowed_decisions": ["approve", "edit", "reject"]},
    "send_email": {"allowed_decisions": ["approve", "edit", "reject"]},

    # Medium risk: no editing allowed
    "write_file": {"allowed_decisions": ["approve", "reject"]},

    # Low risk: no interrupts
    "read_file": False,
    "list_files": False,
}

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