ipybox

ipybox is a Python code execution sandbox with first-class support for programmatic MCP tool calling. It generates typed Python tool APIs from MCP server tool schemas, supporting both local stdio and remote HTTP servers.

Code that calls the generated API executes in a sandboxed IPython kernel. The API delegates MCP tool execution to a separate environment that enforces tool call approval, requiring applications to accept or reject each tool call.

Capabilities

Capability	Description
Stateful code execution	State persists across executions in IPython kernels
Lightweight sandboxing	Kernel isolation via Anthropic's sandbox-runtime
Programmatic MCP tool calling	MCP tools called via Python code, not JSON directly
MCP tool call approval	Every MCP tool call requires application-level approval
Python tool API generation	Functions and models generated from MCP tool schemas
Any MCP server	Supports stdio, Streamable HTTP, and SSE transports
Any Python package	Install and use any Python package in IPython kernels
Local code execution	No cloud dependencies, everything runs on your machine

Usage

Component	Description
Python SDK	Python API for building applications on ipybox
MCP server	ipybox as MCP server for code actions and programmatic tool calling
Claude Code plugin	Plugin that bundles the ipybox MCP server and a code action skill

Agent integration

ipybox is designed for agents that act by executing Python code rather than issuing JSON tool calls. This code action approach enables tool composition and intermediate result processing in a single inference pass, keeping intermediate results out of the agent's context window.

Code actions are also key for agents to improve themselves and their tool libraries by capturing successful experience as executable knowledge. Agent-generated code cannot be trusted and requires sandboxed execution with application-level approval for every MCP tool call.

freeact

Freeact is an agent harness and CLI tool built on ipybox.