Handler

Handler is an open-source A2A protocol client for your terminal.

Use the TUI or CLI to send messages, manage tasks, and inspect agent cards. An included MCP server lets your AI assistant talk to A2A agents too.

Install

uv tool install a2a-handler

Or with pipx / pip:

pipx install a2a-handler   # or: pip install a2a-handler

Quick Start

handler tui                              # launch the interactive TUI
handler message send URL "hello"         # send a message from the CLI
handler card get URL                     # fetch an agent card
handler mcp                              # start the MCP server
handler server run agent                 # run the bundled reference agent

Run Without Installing

uvx --from a2a-handler handler           # or: pipx run a2a-handler

Servers

Handler supports named servers in $XDG_CONFIG_HOME/handler/servers.toml (global) and .handler/servers.toml (repo-local).

version = 1

[servers.local]
url = "http://localhost:8000"

[servers.local.auth]
type = "bearer"
env = "HANDLER_LOCAL_TOKEN"

See docs/ for the full auth reference covering bearer, API key, mTLS, and OAuth2.

Development

A hermetic dev environment is available via Nix:

nix develop

The Mintlify docs source lives in docs/.

See CONTRIBUTING.md for guidelines.