deep-agents-core

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

Audit 0.4.1 · source sha 3d4070fc0837 · 20 Oct 2026Report an issue or request a re-scan

• Publisherlangchain-ai GitHub organizationOwner of the repository this skill is read from
• Source folderlangchain-ai/langchain-skills/config/skills/deep-agents-coreThe exact folder we audited
• LicenceMITAs the repository states it
• Commit pinned for this verdict3d4070fc0837A new audit runs when the source changes
• Repository statusNot archivedLast push 1 day ago
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: INVOKE THIS SKILL when building ANY Deep Agents application. Covers create_deep_agent(), harness architecture, SKILL.md format, and configuration options.

---
name: deep-agents-core
description: "INVOKE THIS SKILL when building ANY Deep Agents application. Covers create_deep_agent(), harness architecture, SKILL.md format, and configuration options."
---

<overview>
Deep Agents are an opinionated agent framework built on LangChain/LangGraph with built-in middleware:

- **Task Planning**: TodoListMiddleware for breaking down complex tasks
- **Context Management**: Filesystem tools with pluggable backends
- **Task Delegation**: SubAgent middleware for spawning specialized agents
- **Long-term Memory**: Persistent storage across threads via Store
- **Human-in-the-loop**: Approval workflows for sensitive operations
- **Skills**: On-demand loading of specialized capabilities

The agent harness provides these capabilities automatically - you configure, not implement.
</overview>

<when-to-use>

| Use Deep Agents When | Use LangChain's create_agent When |
|---------------------|-----------------------------------|
| Multi-step tasks requiring planning | Simple, single-purpose tasks |
| Large context requiring file management | Context fits in a single prompt |
| Need for specialized subagents | Single agent is sufficient |
| Persistent memory across sessions | Ephemeral, single-session work |

</when-to-use>

<middleware-selection>

| If you need to... | Middleware | Notes |
|------------------|------------|-------|
| Track complex tasks | TodoListMiddleware | Default enabled |
| Manage file context | FilesystemMiddleware | Configure backend |
| Delegate work | SubAgentMiddleware | Add custom subagents |
| Add human approval | HumanInTheLoopMiddleware | Requires checkpointer |
| Load skills | SkillsMiddleware | Provide skill directories |
| Access memory | MemoryMiddleware | Requires Store instance |

</middleware-selection>

<ex-basic-agent>
<python>
Create a basic deep agent with a custom tool and invoke it with a user message.

```python
from deepagents import create_deep_agent
from langchain.tools import tool

@tool
def get_weather(city: str) -> str:
    """Get the weather for a given city."""
    return f"It is always sunny in {city}"

agent = create_deep_agent(
    model="claude-sonnet-4-5-20250929",
    tools=[get_weather],
    system_prompt="You are a helpful assistant"
)

config = {"configurable": {"thread_id": "user-123"}}
result = agent.invoke({
    "messages": [{"role": "user", "content": "What's the weather in Tokyo?"}]
}, config=config)
```
</python>
<typescript>
Create a basic deep agent with a custom tool and invoke it with a user message.

```typescript
import { createDeepAgent } from "deepagents";
import { tool } from "@langchain/core/tools";
import { z } from "zod";

const getWeather = tool(
  async ({ city }) => `It is always sunny in ${city}`,
  { name: "get_weather", description: "Get weather for a city", schema: z.object({ city: z.string() }) }
);

const agent = await createDeepAgent({
  model: "claude-sonnet-4-5-20250929",
  tools: [getWeather],
  systemPrompt: "You are a helpful assistant"
});

const config = { configurable: { thread_id: "user-123" } };
const result = await agent.invoke({
  messages: [{ role: "user", content: "What's the weather in Tokyo?" }]
}, config);
```
</typescript>
</ex-basic-agent>

<ex-full-configuration>
<python>
Configure a deep agent with all available options including subagents, skills, and persistence.

```python
from deepagents import create_deep_agent
from deepagents.backends import FilesystemBackend
from langgraph.checkpoint.memory import MemorySaver
from langgraph.store.memory import InMemoryStore

agent = create_deep_agent(
    name="my-assistant",
    model="claude-sonnet-4-5-20250929",
    tools=[custom_tool1, custom_tool2],
    system_prompt="Custom instructions",
    subagents=[research_agent, code_agent],
    backend=FilesystemBackend(root_dir=".", virtual_mode=True),
    interrupt_on={"write_file": True},
    skills=["./skills/"],
    checkpointer=MemorySaver(),
    store=InMemoryStore()
)
```
</python>
<typescript>
Configure a deep agent with all available options including subagents, skills, and persistence.

```typescript
import { createDeepAgent, FilesystemBackend } from "deepagents";
import { MemorySaver, InMemoryStore } from "@langchain/langgraph";

const agent = await createDeepAgent({
  name: "my-assistant",
  model: "claude-sonnet-4-5-20250929",
  tools: [customTool1, customTool2],
  systemPrompt: "Custom instructions",
  subagents: [researchAgent, codeAgent],
  backend: new FilesystemBackend({ rootDir: ".", virtualMode: true }),
  interruptOn: { write_file: true },
  skills: ["./skills/"],
  checkpointer: new MemorySaver(),
  store: new InMemoryStore()
});
```
</typescript>
</ex-full-configuration>

<built-in-tools>
Every deep agent has access to:

1. **Planning**: `write_todos` - Track multi-step tasks
2. **Filesystem**: `ls`, `read_file`, `write_file`, `edit_file`, `glob`, `grep`
3. **Delegation**: `task` - Spawn specialized subagents
</built-in-tools>

---

## SKILL.md Format

<skill-md-format>
Skills use **progressive disclosure** - agents only load content when relevant.

### Directory Structure

```
skills/
└── my-skill/
    ├── SKILL.md        # Required: main skill file
    ├── examples.py     # Optional: supporting files
    └── templates/      # Optional: templates
```

### SKILL.md Format

```markdown
---
name: my-skill
description: Clear, specific description of what this skill does
---

# Skill Name

## Overview
Brief explanation of the skill's purpose.

## When to Use
Conditions when this skill applies.

## Instructions
Step-by-step guidance for the agent.
```
</skill-md-format>

<skills-vs-memory>

| Skills | Memory (AGENTS.md) |
|--------|-------------------|
| On-demand loading | Always loaded at startup |
| Task-specific instructions | General preferences |
| Large documentation | Compact context |
| SKILL.md in directories | Single AGENTS.md file |

</skills-vs-memory>

<ex-skills-with-filesystem-backend>
<python>
Set up an agent with skills directory 

Excerpt, first 6,000 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

git clone https://github.com/langchain-ai/langchain-skills
git -C langchain-skills checkout 3d4070fc0837

Works in

1. 2026-10-20
   ✓SAFE B 89 / 100

   first audit · source 3d4070fc0837

Questions about deep-agents-core

• github.com/langchain-ai/langchain-skills/tree/main/config/skills — the audited source at commit 3d4070fc0837 and every finding aboveObserved · 20 Oct 2026

Spotted something wrong? Report a correction · Methodology