SmolAgents - Hugging Face AI Agent Framework

SmolAgents is a minimalist Python library (~1000 lines) for building AI agents that write and execute code. It emphasizes simplicity, security, and model-agnostic design.

Installation

pip install smolagents                    # Core library
pip install 'smolagents[toolkit]'         # With default tools (web search, etc.)
pip install 'smolagents[litellm]'         # LiteLLM for OpenAI/Anthropic
pip install 'smolagents[transformers]'    # Local model support
pip install 'smolagents[mcp]'             # MCP server integration
pip install 'smolagents[telemetry]'       # OpenTelemetry support

Core Concepts

Agent Types

CodeAgent - Primary agent that writes Python code to execute actions:

from smolagents import CodeAgent, InferenceClientModel

model = InferenceClientModel()  # Default: Qwen/Qwen2.5-Coder-32B-Instruct
agent = CodeAgent(tools=[], model=model)
result = agent.run("Calculate the first 20 Fibonacci numbers")

ToolCallingAgent - Uses JSON-based tool calls (no code execution):

from smolagents import ToolCallingAgent, InferenceClientModel

agent = ToolCallingAgent(tools=[], model=InferenceClientModel())
agent.run("Get the title of https://huggingface.co/blog")

Model Configuration

Hugging Face Inference API (recommended for quick start):

from smolagents import InferenceClientModel

# Default model
model = InferenceClientModel()

# Specific model with provider
model = InferenceClientModel(
    model_id="meta-llama/Llama-3.3-70B-Instruct",
    provider="together",  # or "sambanova", "fireworks", etc.
    token="YOUR_HF_TOKEN"
)

LiteLLM (100+ providers):

from smolagents import LiteLLMModel

# Anthropic
model = LiteLLMModel(
    model_id="anthropic/claude-3-5-sonnet-latest",
    api_key="YOUR_ANTHROPIC_API_KEY"
)

# OpenAI
model = LiteLLMModel(model_id="gpt-4o", api_key="YOUR_OPENAI_API_KEY")

Local Transformers:

from smolagents import TransformersModel

model = TransformersModel(
    model_id="Qwen/Qwen2.5-Coder-32B-Instruct",
    max_new_tokens=4096,
    device_map="auto"
)

Ollama (local):

from smolagents import LiteLLMModel

model = LiteLLMModel(
    model_id="ollama_chat/llama3.2",
    api_base="http://localhost:11434",
    num_ctx=8192  # Important: increase from default 2048
)

OpenAI-compatible endpoints:

from smolagents import OpenAIModel

model = OpenAIModel(
    model_id="deepseek-ai/DeepSeek-R1",
    api_base="https://api.together.xyz/v1/",
    api_key="YOUR_API_KEY"
)

Tools

Built-in Tools

from smolagents import CodeAgent, InferenceClientModel, WebSearchTool, DuckDuckGoSearchTool

agent = CodeAgent(
    tools=[WebSearchTool()],  # or DuckDuckGoSearchTool()
    model=InferenceClientModel(),
    add_base_tools=True  # Adds transcriber, python interpreter
)

Creating Custom Tools

Using @tool decorator (simplest):

from smolagents import tool

@tool
def get_weather(city: str) -> str:
    """
    Gets current weather for a city.
    
    Args:
        city: Name of the city to get weather for.
    """
    # Implementation
    return f"Weather in {city}: Sunny, 22°C"

Using Tool class (more control):

from smolagents import Tool

class HFModelDownloadsTool(Tool):
    name = "model_download_counter"
    description = "Returns the most downloaded model for a given task on HuggingFace Hub."
    inputs = {
        "task": {"type": "string", "description": "The ML task (e.g., 'text-to-video')"}
    }
    output_type = "string"

    def forward(self, task: str) -> str:
        from huggingface_hub import list_models
        model = next(iter(list_models(filter=task, sort="downloads", direction=-1)))
        return model.id

Loading Tools from Hub

from smolagents import load_tool

image_tool = load_tool("m-ric/text-to-image", trust_remote_code=True)
agent = CodeAgent(tools=[image_tool], model=model)

Loading from Gradio Spaces

from smolagents import Tool

image_generator = Tool.from_space(
    "black-forest-labs/FLUX.1-schnell",
    name="image_generator",
    description="Generates images from text prompts"
)

LangChain Tool Integration

from smolagents import Tool
from langchain.agents import load_tools

search_tool = Tool.from_langchain(load_tools(["serpapi"])[0])
agent = CodeAgent(tools=[search_tool], model=model)

MCP Server Integration

from smolagents import ToolCollection, CodeAgent
from mcp import StdioServerParameters

server_params = StdioServerParameters(
    command="uvx",
    args=["mcp-server-fetch"]
)

with ToolCollection.from_mcp(server_params, trust_remote_code=True) as tools:
    agent = CodeAgent(tools=[*tools.tools], model=model)
    agent.run("Fetch the homepage of huggingface.co")

Managing Agent Tools

# Add tool dynamically
agent.tools[new_tool.name] = new_tool

# List tools
print(agent.tools.keys())

Agent Configuration

Key Parameters

agent = CodeAgent(
    tools=[...],
    model=model,
    max_steps=10,                          # Max reasoning steps
    verbosity_level=2,                     # 0=silent, 1=steps, 2=detailed
    planning_interval=3,                   # Enable planning every N steps
    additional_authorized_imports=["numpy", "pandas"],  # Allow imports
    add_base_tools=True,                   # Include default tools
    step_callbacks=[my_callback],          # Custom callbacks per step
)

Running Agents

# Basic run
result = agent.run("Your task here")

# With additional context
result = agent.run(
    "Generate an image based on this prompt",
    additional_args={"user_prompt": "A cat in space"}
)

# Continue conversation (preserve memory)
result = agent.run("Follow-up question", reset=False)

Memory Management

Accessing Memory

from smolagents import ActionStep

# System prompt
print(agent.memory.system_prompt.system_prompt)

# Task
print(agent.memory.steps[0].task)

# Iterate through steps
for step in agent.memory.steps:
    if isinstance(step, ActionStep):
        if step.error:
            print(f"Step {step.step_number} error: {step.error}")
        else:
            print(f"Step {step.step_number}: {step.observations}")

Step-by-Step Execution

from smolagents import CodeAgent, InferenceClientModel, ActionStep, TaskStep

agent = CodeAgent(tools=[], model=InferenceClientModel(), verbosity_level=1)
agent.python_executor.send_tools({**agent.tools})

task = "What is the 20th Fibonacci number?"
agent.memory.steps.append(TaskStep(task=task, task_images=[]))

final_answer = None
step_number = 1

while final_answer is None and step_number <= 10:
    memory_step = ActionStep(step_number=step_number, observations_images=[])
    final_answer = agent.step(memory_step)
    agent.memory.steps.append(memory_step)
    step_number += 1

print("Answer:", final_answer)

Step Callbacks

from smolagents import ActionStep, CodeAgent

def log_step(memory_step: ActionStep, agent: CodeAgent) -> None:
    print(f"Completed step {memory_step.step_number}")
    # Modify memory if needed
    if memory_step.step_number > 5:
        memory_step.observations_images = None  # Clear images to save tokens

agent = CodeAgent(
    tools=[...],
    model=model,
    step_callbacks=[log_step]
)

Replay Execution

agent.run("Your task")
agent.replay()  # Replay the last execution

Multi-Agent Systems

Basic Multi-Agent Setup

from smolagents import CodeAgent, InferenceClientModel, WebSearchTool

model = InferenceClientModel()

# Specialist agent
web_agent = CodeAgent(
    tools=[WebSearchTool()],
    model=model,
    name="web_search_agent",
    description="Runs web searches. Give it your query as an argument."
)

# Manager agent
manager_agent = CodeAgent(
    tools=[],
    model=model,
    managed_agents=[web_agent],
    additional_authorized_imports=["pandas", "numpy"]
)

manager_agent.run("Who is the CEO of Hugging Face?")

With ToolCallingAgent

from smolagents import ToolCallingAgent, CodeAgent, WebSearchTool

web_agent = ToolCallingAgent(
    tools=[WebSearchTool(), visit_webpage],
    model=model,
    max_steps=10,
    name="web_search_agent",
    description="Runs web searches for you."
)

manager = CodeAgent(
    tools=[],
    model=model,
    managed_agents=[web_agent]
)

Secure Code Execution

Local Python Executor (Default)

Built-in security:

• Restricted imports (must be explicitly authorized)
• Operation count limits (prevents infinite loops)
• AST-based execution (no raw eval)

agent = CodeAgent(
    tools=[],
    model=model,
    additional_authorized_imports=["numpy", "pandas", "requests"]
)

E2B Sandbox

# pip install e2b-code-interpreter python-dotenv
# Set E2B_API_KEY environment variable

from smolagents import CodeAgent, InferenceClientModel

agent = CodeAgent(
    tools=[],
    model=InferenceClientModel(),
    executor_type="e2b",
    executor_kwargs={"api_key": "YOUR_E2B_API_KEY"},
    additional_authorized_imports=["requests"]
)

agent.run("Calculate something complex")

Docker Sandbox

agent = CodeAgent(
    tools=[],
    model=InferenceClientModel(),
    executor_type="docker"
)

Blaxel Sandbox

from smolagents import CodeAgent, InferenceClientModel

with CodeAgent(model=InferenceClientModel(), tools=[], executor_type="blaxel") as agent:
    agent.run("Give me the 100th Fibonacci number")
# Sandbox automatically cleaned up

Common Patterns

Text-to-SQL Agent

from smolagents import tool, CodeAgent, InferenceClientModel
from sqlalchemy import create_engine, text

engine = create_engine("sqlite:///database.db")

@tool
def sql_engine(query: str) -> str:
    """
    Execute SQL queries on the database.
    
    Args:
        query: SQL query to execute.
    """
    with engine.connect() as conn:
        result = conn.execute(text(query))
        return str(result.fetchall())

agent = CodeAgent(
    tools=[sql_engine],
    model=InferenceClientModel()
)

agent.run("What are the top 5 customers by total purchases?")

Agentic RAG

from smolagents import tool, CodeAgent, InferenceClientModel

@tool
def retriever_tool(query: str) -> str:
    """
    Retrieves relevant documents from the knowledge base.
    
    Args:
        query: Search query for the knowledge base.
    """
    # Your retrieval logic here
    return "Retrieved documents..."

agent = CodeAgent(
    tools=[retriever_tool],
    model=InferenceClientModel(),
    max_steps=4,
    verbosity_level=2
)

agent.run("What does our documentation say about authentication?")

Web Browser Agent

from smolagents import CodeAgent, InferenceClientModel, tool
import helium

@tool  
def go_back() -> str:
    """Go back to the previous page."""
    helium.go_back()
    return "Navigated back"

@tool
def search_item_ctrl_f(text: str) -> str:
    """
    Search for text on the current page.
    
    Args:
        text: Text to search for.
    """
    elements = helium.find_all(helium.Text(text))
    return f"Found {len(elements)} matches"

agent = CodeAgent(
    tools=[go_back, search_item_ctrl_f],
    model=InferenceClientModel(model_id="Qwen/Qwen2-VL-72B-Instruct"),  # VLM for vision
    additional_authorized_imports=["helium"],
    max_steps=20
)

Gradio UI

from smolagents import CodeAgent, InferenceClientModel, GradioUI, load_tool

image_tool = load_tool("m-ric/text-to-image")
agent = CodeAgent(tools=[image_tool], model=InferenceClientModel())

GradioUI(agent).launch()

CLI Usage

# Basic agent
smolagent "Plan a trip to Tokyo" \
    --model-type InferenceClientModel \
    --model-id "Qwen/Qwen2.5-Coder-32B-Instruct" \
    --tools web_search

# Web browsing agent
webagent "Go to example.com and find the pricing page" \
    --model-type LiteLLMModel \
    --model-id gpt-4o

# Interactive mode
smolagent  # Launches setup wizard

Telemetry & Debugging

# Enable OpenTelemetry tracing
# pip install 'smolagents[telemetry]'

from phoenix.trace import init_tracing

init_tracing(service_name="my_agent")

agent = CodeAgent(tools=[...], model=model)
agent.run("Your task")

Best Practices

1. Start simple: Use InferenceClientModel() with defaults
2. Use planning for complex tasks: planning_interval=3
3. Limit steps: Set reasonable max_steps (10-20)
4. Authorize imports explicitly: Security-first approach
5. Use sandboxing in production: E2B, Docker, or Blaxel
6. Add verbosity during development: verbosity_level=2
7. Use ToolCallingAgent when code execution isn't needed
8. Specialize agents in multi-agent systems

Additional Resources

• Documentation: https://huggingface.co/docs/smolagents
• GitHub: https://github.com/huggingface/smolagents
• HF Agents Course: https://huggingface.co/learn/agents-course
• Model specifications: See references/models.md
• Advanced patterns: See references/patterns.md