Setting the chapter. One moment.
Skills
Chapter 3 of 22
INVOKE THIS SKILL when using subagents, task planning, or human approval in Deep Agents.
3 minutes · 635 words · 5 sections
task tool to specialized agentswrite_todos toolAll three are automatically included in create_deep_agent().
| 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/"], ...}]
)| 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]) -> NoneEach 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| 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,
)task, write_todos)# 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,
)Install this repository
npx skills add langchain-ai/langchain-skills/plugin marketplace add langchain-ai/langchain-skillsSkills install per repository, not per chapter — the CLI has no documented per-skill form, so we do not print one.
INVOKE THIS SKILL when using subagents, task planning, or human approval in Deep Agents. Covers SubAgentMiddleware, TodoList for planning, and HITL interrupts.
The verbatim description from this skill’s front matter — the string an agent matches on to decide whether to load it.
main, last pushed 7 August 2026.SKILL.md, not by matching a directory convention. One layout observed: config/skills/*/SKILL.md..claude-plugin/marketplace.json by LangChain, declaring 1 plugin. It is read for editorial metadata only — never as the skill index, which is always the repository tree./langchain-ai/langchain-skills.md, and each chapter at its own .md URL.