dkmqflx - SubAgentMiddleware: Delegate work via
tasktool to specialized agents - TodoListMiddleware: Plan and track tasks via
write_todostool - HumanInTheLoopMiddleware: Require approval before sensitive operations
All three are automatically included in create_deep_agent().
Subagents (Task Delegation)
| Use Subagents When | Use Main Agent When |
|---|---|
| Task needs specialized tools | General-purpose tools sufficient |
| Want to isolate complex work | Single-step operation |
| Need clean context for main agent | Context bloat acceptable |
Default subagent: "general-purpose" - automatically available with same tools/config as main agent.
from deepagents import create_deep_agent
from langchain.tools import tool
@tool
def search_papers(query: str) -> str:
"""Search academic papers."""
return f"Found 10 papers about {query}"
agent = create_deep_agent(
subagents=[
{
"name": "researcher",
"description": "Conduct web research and compile findings",
"system_prompt": "Search thoroughly, return concise summary",
"tools": [search_papers],
}
]
)
# Main agent delegates: task(agent="researcher", instruction="Research AI trends")
import { createDeepAgent } from "deepagents";
import { tool } from "@langchain/core/tools";
import { z } from "zod";
const searchPapers = tool(
async ({ query }) => `Found 10 papers about ${query}`,
{ name: "search_papers", description: "Search papers", schema: z.object({ query: z.string() }) }
);
const agent = await createDeepAgent({
subagents: [
{
name: "researcher",
description: "Conduct web research and compile findings",
systemPrompt: "Search thoroughly, return concise summary",
tools: [searchPapers],
}
]
});
// Main agent delegates: task(agent="researcher", instruction="Research AI trends")
from deepagents import create_deep_agent
from langgraph.checkpoint.memory import MemorySaver
agent = create_deep_agent(
subagents=[
{
"name": "code-deployer",
"description": "Deploy code to production",
"system_prompt": "You deploy code after tests pass.",
"tools": [run_tests, deploy_to_prod],
"interrupt_on": {"deploy_to_prod": True}, # Require approval
}
],
checkpointer=MemorySaver() # Required for interrupts
)
# WRONG: Subagents don't remember previous calls
# task(agent='research', instruction='Find data')
# task(agent='research', instruction='What did you find?') # Starts fresh!
# CORRECT: Complete instructions upfront
# task(agent='research', instruction='Find data on AI, save to /research/, return summary')
// WRONG: Subagents don't remember previous calls
// task research: Find data
// task research: What did you find? // Starts fresh!
// CORRECT: Complete instructions upfront
// task research: Find data on AI, save to /research/, return summary
# WRONG: Custom subagent won't have main agent's skills
agent = create_deep_agent(
skills=["/main-skills/"],
subagents=[{"name": "helper", ...}] # No skills inherited
)
# CORRECT: Provide skills explicitly (general-purpose subagent DOES inherit)
agent = create_deep_agent(
skills=["/main-skills/"],
subagents=[{"name": "helper", "skills": ["/helper-skills/"], ...}]
)
TodoList (Task Planning)
| Use TodoList When | Skip TodoList When |
|---|---|
| Complex multi-step tasks | Simple single-action tasks |
| Long-running operations | Quick operations (< 3 steps) |
write_todos(todos: list[dict]) -> None
Each todo item has:
content: Description of the taskstatus: One of"pending","in_progress","completed"
from deepagents import create_deep_agent
agent = create_deep_agent() # TodoListMiddleware included by default
result = agent.invoke({
"messages": [{"role": "user", "content": "Create a REST API: design models, implement CRUD, add auth, write tests"}]
}, config={"configurable": {"thread_id": "session-1"}})
# Agent's planning via write_todos:
# [
# {"content": "Design data models", "status": "in_progress"},
# {"content": "Implement CRUD endpoints", "status": "pending"},
# {"content": "Add authentication", "status": "pending"},
# {"content": "Write tests", "status": "pending"}
# ]
import { createDeepAgent } from "deepagents";
const agent = await createDeepAgent(); // TodoListMiddleware included
const result = await agent.invoke({
messages: [{ role: "user", content: "Create a REST API: design models, implement CRUD, add auth, write tests" }]
}, { configurable: { thread_id: "session-1" } });
result = agent.invoke({...}, config={"configurable": {"thread_id": "session-1"}})
# Access todo list from final state
todos = result.get("todos", [])
for todo in todos:
print(f"[{todo['status']}] {todo['content']}")
# WRONG: Fresh state each time without thread_id
agent.invoke({"messages": [...]})
# CORRECT: Use thread_id
config = {"configurable": {"thread_id": "user-session"}}
agent.invoke({"messages": [...]}, config=config) # Todos preserved
Human-in-the-Loop (Approval Workflows)
| Use HITL When | Skip HITL When |
|---|---|
| High-stakes operations (DB writes, deployments) | Read-only operations |
| Compliance requires human oversight | Fully automated workflows |
from deepagents import create_deep_agent
from langgraph.checkpoint.memory import MemorySaver
agent = create_deep_agent(
interrupt_on={
"write_file": True, # All decisions allowed
"execute_sql": {"allowed_decisions": ["approve", "reject"]},
"read_file": False, # No interrupts
},
checkpointer=MemorySaver() # REQUIRED for interrupts
)
import { createDeepAgent } from "deepagents";
import { MemorySaver } from "@langchain/langgraph";
const agent = await createDeepAgent({
interruptOn: {
write_file: true,
execute_sql: { allowedDecisions: ["approve", "reject"] },
read_file: false,
},
checkpointer: new MemorySaver() // REQUIRED
});
from deepagents import create_deep_agent
from langgraph.checkpoint.memory import MemorySaver
from langgraph.types import Command
agent = create_deep_agent(
interrupt_on={"write_file": True},
checkpointer=MemorySaver()
)
config = {"configurable": {"thread_id": "session-1"}}
# Step 1: Agent proposes write_file - execution pauses
result = agent.invoke({
"messages": [{"role": "user", "content": "Write config to /prod.yaml"}]
}, config=config)
# Step 2: Check for interrupts
state = agent.get_state(config)
if state.next:
print(f"Pending action")
# Step 3: Approve and resume
result = agent.invoke(Command(resume={"decisions": [{"type": "approve"}]}), config=config)
import { createDeepAgent } from "deepagents";
import { MemorySaver, Command } from "@langchain/langgraph";
const agent = await createDeepAgent({
interruptOn: { write_file: true },
checkpointer: new MemorySaver()
});
const config = { configurable: { thread_id: "session-1" } };
// Step 1: Agent proposes write_file - execution pauses
let result = await agent.invoke({
messages: [{ role: "user", content: "Write config to /prod.yaml" }]
}, config);
// Step 2: Check for interrupts
const state = await agent.getState(config);
if (state.next) {
console.log("Pending action");
}
// Step 3: Approve and resume
result = await agent.invoke(
new Command({ resume: { decisions: [{ type: "approve" }] } }), config
);
result = agent.invoke(
Command(resume={"decisions": [{"type": "reject", "message": "Run tests first"}]}),
config=config,
)
const result = await agent.invoke(
new Command({ resume: { decisions: [{ type: "reject", message: "Run tests first" }] } }),
config,
);
result = agent.invoke(
Command(resume={"decisions": [{
"type": "edit",
"edited_action": {
"name": "execute_sql",
"args": {"query": "DELETE FROM users WHERE last_login < '2020-01-01' LIMIT 100"},
},
}]}),
config=config,
)
- Subagent names, tools, models, system prompts
- Which tools require approval
- Allowed decision types per tool
- TodoList content and structure
What Agents CANNOT Configure
- Tool names (
task,write_todos) - HITL protocol (approve/edit/reject structure)
- Skip checkpointer requirement for interrupts
- Make subagents stateful (they're ephemeral)
# WRONG
agent = create_deep_agent(interrupt_on={"write_file": True})
# CORRECT
agent = create_deep_agent(interrupt_on={"write_file": True}, checkpointer=MemorySaver())
// WRONG
const agent = await createDeepAgent({ interruptOn: { write_file: true } });
// CORRECT
const agent = await createDeepAgent({ interruptOn: { write_file: true }, checkpointer: new MemorySaver() });
# WRONG: Can't resume without thread_id
agent.invoke({"messages": [...]})
# CORRECT
config = {"configurable": {"thread_id": "session-1"}}
agent.invoke({...}, config=config)
# Resume with Command using same config
agent.invoke(Command(resume={"decisions": [{"type": "approve"}]}), config=config)
// WRONG: Can't resume without thread_id
await agent.invoke({ messages: [...] });
// CORRECT
const config = { configurable: { thread_id: "session-1" } };
await agent.invoke({ messages: [...] }, config);
// Resume with Command using same config
await agent.invoke(new Command({ resume: { decisions: [{ type: "approve" }] } }), config);
result = agent.invoke({...}, config=config) # Step 1: triggers interrupt
if "__interrupt__" in result: # Step 2: check for interrupt
result = agent.invoke( # Step 3: resume
Command(resume={"decisions": [{"type": "approve"}]}),
config=config,
)