Handler

Handler is an open-source A2A Protocol client and developer toolkit.

It provides a CLI and TUI for communicating with remote agents, an MCP server for bridging AI assistants into the A2A ecosystem, a reference server agent implementation, push notification support, and agent card validation. Whether you're building agents, integrating with existing ones, or exploring agent-to-agent communication, Handler gives you the observability and control you need from your terminal.

Who is Handler For?

Handler is for developers, researchers, and teams working with AI agents. If you're building agents that speak A2A, Handler helps you test and debug them. If you're integrating with existing A2A agents, Handler gives you a fast way to explore their capabilities. If you want your AI assistant to communicate with other agents, Handler's MCP server bridges that gap. And if you're just curious about agent-to-agent communication, Handler is a great place to start.

Get Started

Install with uv:

uv tool install a2a-handler

Or run in an ephemeral environment:

uvx --from a2a-handler handler

For usage documentation, see the Handler docs.

Contributing

See CONTRIBUTING.md.