Stirrup is a lightweight framework, or starting point template, for building agents. It differs from other agent frameworks by:
- Working with the model, not against it: Stirrup gets out of the way and lets the model choose its own approach to completing tasks (similar to Claude Code). Many frameworks impose rigid workflows that can degrade results.
- Best practices and tools built-in: We analyzed the leading agents (Claude Code, Codex, and others) to understand and incorporate best practices relating to topics like context management and foundational tools (e.g., code execution).
- Fully customizable: Use Stirrup as a package or as a starting template to build your own fully customized agents.
- Essential tools built-in:
- Online search / web browsing
- Code execution (local, Docker container, E2B sandbox)
- MCP client
- Document input and output
- Skills system: Extend agent capabilities with modular, domain-specific instruction packages
- Flexible tool execution: A generic
Toolclass allows easy tool definition and extension - Context management: Automatically summarizes conversation history when approaching context limits
- Flexible provider support: Pre-built support for OpenAI-compatible APIs and LiteLLM, or bring your own client
- Multimodal support: Process images, video, and audio with automatic format conversion
# Core framework pip install stirrup # or: uv add stirrup # With all optional components pip install 'stirrup[all]' # or: uv add 'stirrup[all]' # Individual extras pip install 'stirrup[litellm]' # or: uv add 'stirrup[litellm]' pip install 'stirrup[docker]' # or: uv add 'stirrup[docker]' pip install 'stirrup[e2b]' # or: uv add 'stirrup[e2b]' pip install 'stirrup[mcp]' # or: uv add 'stirrup[mcp]'
import asyncio from stirrup import Agent from stirrup.clients.chat_completions_client import ChatCompletionsClient async def main() -> None: """Run an agent that searches the web and creates a chart.""" # Create client using ChatCompletionsClient # Automatically uses OPENROUTER_API_KEY environment variable client = ChatCompletionsClient( base_url="https://openrouter.ai/api/v1", model="anthropic/claude-sonnet-4.5", ) # As no tools are provided, the agent will use the default tools, which consist of: # - Web tools (web search and web fetching, note web search requires BRAVE_API_KEY) # - Local code execution tool (to execute shell commands) agent = Agent(client=client, name="agent", max_turns=15) # Run with session context - handles tool lifecycle, logging and file outputs async with agent.session(output_dir="./output/getting_started_example") as session: finish_params, history, metadata = await session.run( """ What is the population of Australia over the last 3 years? Search the web to find out and create a simple chart using matplotlib showing the current population per year.""" ) print("Finish params: ", finish_params) print("History: ", history) print("Metadata: ", metadata) if __name__ == "__main__": asyncio.run(main())
Note: This example uses OpenRouter. Set
OPENROUTER_API_KEYin your environment before running. Web search requires aBRAVE_API_KEY. The agent will still work without it, but web search will be unavailable.
For using Stirrup as a foundation for your own fully customized agent, you can clone and import Stirrup locally:
# Clone the repository git clone https://github.com/ArtificialAnalysis/Stirrup.git cd stirrup # Install in editable mode pip install -e . # or: uv venv && uv pip install -e . # Or with all optional dependencies pip install -e '.[all]' # or: uv venv && uv pip install -e '.[all]'
See the Full Customization guide for more details.
Agent- Configures and runs the agent loop until a finish tool is called or max turns reachedsession()- Context manager that sets up tools, manages files, and handles cleanupTool- Define tools with Pydantic parametersToolProvider- Manage tools that require lifecycle (connections, temp directories, etc.)DEFAULT_TOOLS- Standard tools included by default: code execution and web tools
For non-OpenAI providers, change the base URL of the ChatCompletionsClient, use the LiteLLMClient (requires installation of optional stirrup[litellm] dependencies), or create your own client.
# Create client using Deepseek's OpenAI-compatible endpoint client = ChatCompletionsClient( base_url="https://api.deepseek.com", model="deepseek-chat", # or "deepseek-reasoner" for R1 api_key=os.environ["DEEPSEEK_API_KEY"], ) agent = Agent(client=client, name="deepseek_agent")
# Ensure LiteLLM is added with: pip install 'stirrup[litellm]' # or: uv add 'stirrup[litellm]' # Create LiteLLM client for Anthropic Claude # See https://docs.litellm.ai/docs/providers for all supported providers client = LiteLLMClient( model_slug="anthropic/claude-sonnet-4-5", max_tokens=200_000, ) # Pass client to Agent - model info comes from client.model_slug agent = Agent( client=client, name="claude_agent", )
See LiteLLM Example or Deepseek Example for complete examples.
When you create an Agent without specifying tools, it uses DEFAULT_TOOLS:
| Tool Provider | Tools Provided | Description |
|---|---|---|
LocalCodeExecToolProvider |
code_exec |
Execute shell commands in an isolated temp directory |
WebToolProvider |
web_fetch, web_search |
Fetch web pages and search (search requires BRAVE_API_KEY) |
import asyncio from stirrup import Agent from stirrup.clients.chat_completions_client import ChatCompletionsClient from stirrup.tools import CALCULATOR_TOOL, DEFAULT_TOOLS # Create client for OpenRouter client = ChatCompletionsClient( base_url="https://openrouter.ai/api/v1", model="anthropic/claude-sonnet-4.5", ) # Create agent with default tools + calculator tool agent = Agent( client=client, name="web_calculator_agent", tools=[*DEFAULT_TOOLS, CALCULATOR_TOOL], )
from pydantic import BaseModel, Field from stirrup import Agent, Tool, ToolResult, ToolUseCountMetadata from stirrup.clients.chat_completions_client import ChatCompletionsClient from stirrup.tools import DEFAULT_TOOLS class GreetParams(BaseModel): """Parameters for the greet tool.""" name: str = Field(description="Name of the person to greet") formal: bool = Field(default=False, description="Use formal greeting") def greet(params: GreetParams) -> ToolResult[ToolUseCountMetadata]: greeting = f"Good day, {params.name}." if params.formal else f"Hey {params.name}!" return ToolResult( content=greeting, metadata=ToolUseCountMetadata(), ) GREET_TOOL = Tool( name="greet", description="Greet someone by name", parameters=GreetParams, executor=greet, ) # Create client for OpenRouter client = ChatCompletionsClient( base_url="https://openrouter.ai/api/v1", model="anthropic/claude-sonnet-4.5", ) # Add custom tool to default tools agent = Agent( client=client, name="greeting_agent", tools=[*DEFAULT_TOOLS, GREET_TOOL], )
- Getting Started - Installation and first agent tutorial
- Core Concepts - Understand Agent, Tools, and Sessions
- Examples - Working examples for common patterns
- Creating Tools - Build your own tools
Full documentation: artificialanalysis.github.io/Stirrup
Build and serve locally:
uv run mkdocs serve
# Format and lint code uv run ruff format uv run ruff check # Type check uv run ty check # Run tests uv run pytest tests
Licensed under the MIT LICENSE.