> ## Documentation Index
> Fetch the complete documentation index at: https://handler.alduncanson.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Overview

> Handler is a terminal-first A2A client with a TUI, scriptable CLI, MCP bridge, and server configuration for production auth.

# What is Handler?

Handler is an open-source [A2A protocol](https://github.com/a2aproject/A2A)
client for software engineers building, testing, and operating agentic systems.
It gives you a terminal-native control surface for A2A services: an interactive
TUI for exploration, a scriptable CLI with structured output for automation,
and an MCP server so other agents can call A2A services through Handler.

Use Handler when you need to:

* inspect and validate agent cards before debugging deeper protocol issues
* send messages, stream events, and manage tasks from shell scripts or CI
* configure global or repo-scoped A2A servers with bearer, API key, mTLS,
  or OAuth2 client credentials auth
* expose A2A operations as MCP tools for agent harnesses such as Amp or Pi

## Install

Install Handler from the [PyPI package](https://pypi.org/project/a2a-handler/) as a `uv` tool:

```bash theme={null}
uv tool install a2a-handler
```

Or with `pipx`:

```bash theme={null}
pipx install a2a-handler
```

Or with `pip`:

```bash theme={null}
pip install a2a-handler
```

## First commands

Open the interactive terminal UI:

```bash theme={null}
handler tui
```

Inspect an A2A server's agent card:

```bash theme={null}
handler card get --url http://localhost:8000
```

Send a message from the CLI:

```bash theme={null}
handler message send --url http://localhost:8000 --text "hello"
```

Open the full documentation:

```bash theme={null}
handler docs
```

If you want another agent to use Handler through MCP, add `handler mcp` to that
agent's MCP server configuration. See [MCP server](./guides/mcp).

## Choose your path

* [Quickstart](./quickstart) walks through install, first message, and configured servers.
* [TUI and web UI](./guides/tui) covers the interactive workflow.
* [Messages, tasks, and sessions](./guides/messages-tasks) explains CLI automation and structured output.
* [Configured servers](./guides/servers) and [authentication](./guides/authentication) cover production connection configuration.
* [MCP server](./guides/mcp) shows how to let MCP clients call A2A agents through Handler.
* [CLI reference](./reference/cli) lists commands, flags, and machine-readable schema helpers.