Handler

Handler provides an MCP server that bridges AI assistants into the A2A ecosystem and ships with a CLI/TUI for interacting with remote agents. The server is published as the a2a-handler Python package and can be run via Python module execution or through tools like uv/uvx or pipx. Once running, you can use Handler to connect to A2A agents, inspect their capabilities, send messages, and validate agent cards. The included CLI and TUI make it straightforward to explore agent behavior, push notifications, and monitor agent communication all from your terminal.

To use it, install the package using your preferred method (uv, pipx, or pip), then start the server using the recommended command. With uvx or pipx, you can run the server without a full Python environment, which is convenient for ephemeral or sandboxed workflows. The project also provides documentation for usage and developer tooling if you want to dive deeper into A2A protocol capabilities and agent-to-agent communication through the Handler MCP bridge.

Prerequisites:

• Python 3.8+ installed on your system
• Optional: uv/uvx, pipx, or pip depending on installation method

Install methods:

1. Using uv (via uv tool):

uv tool install a2a-handler

2. Using pipx (recommended for isolated environments):

pipx install a2a-handler

3. Using pip (system-wide or user isolation):

pip install a2a-handler

Run the server (any of these methods):

• With uvx (from an ephemeral environment):

uvx --from a2a-handler handler

• With pipx (execute the installed CLI):

pipx run a2a-handler

• Directly with Python (module execution):

python -m a2a_handler

Development environment (optional):

nix develop

This provides Python, uv, and related tooling ready to use.

Notes and tips:

• The MCP server is provided as the a2a-handler package. The recommended run method is via uvx or pipx for isolated environments, but you can also run it directly with Python using -m a2a_handler.
• If you need to customize endpoints or credentials for A2A agents, look for environment variables or configuration options documented in the Handler/A2A docs and ensure those are exposed to the process when starting the MCP server.
• The README references both a CLI and a TUI; use the CLI for quick commands and the TUI for more interactive exploration of agents and capabilities.
• If you encounter permission or path issues after installation, verify that the installed executable is on your PATH or invoke via the full command (e.g., python -m a2a_handler).
• Version compatibility: ensure you’re using a compatible A2A Protocol version (v0.3.0 as indicated by badges) when integrating with other agents or servers.