Handler is an open-source client and comprehensive developer toolkit for the A2A Protocol, designed to facilitate robust agent-to-agent communication and interaction.

Handler is built for developers, researchers, and teams involved with AI agents, providing tools to test, debug, integrate, and operate within the A2A ecosystem.

What are Handler's main features?

It offers a CLI for messaging and session management, a TUI for conversational interaction, an MCP Server for host compatibility, a reference Server Agent, and agent card validation.

How does Handler support AI agent development and debugging?

Handler helps by enabling you to send messages, stream responses, manage sessions, inspect tasks, debug interactions, and validate agent cards against the A2A protocol specification.

Can Handler integrate with other AI platforms or hosts?

Yes, its MCP Server exposes A2A capabilities over the Model Context Protocol, allowing compatibility with various MCP-compatible hosts like Claude, Gemini CLI, and Cursor.

Handler

Name: Handler
Author: alDuncanson

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Provides an open-source A2A Protocol client and comprehensive developer toolkit for robust agent-to-agent communication.

Handler is an enterprise-ready A2A client designed to provide everything needed to communicate with remote agents, inspect tasks, debug interactions, and operate within the agent-to-agent ecosystem. It offers observability and control from the terminal for developers, researchers, and teams exploring A2A, developing their own agents, or running agents in production. Handler's MCP server further enables AI assistants to communicate with other agents, making it a versatile tool for anyone curious about or deeply involved in agent-to-agent communication.

Key Features

0124 GitHub stars

02CLI for sending messages, streaming responses, managing sessions, and validating agent cards.

03TUI (Terminal User Interface) for conversing with agents, inspecting tasks, and viewing artifacts.

04MCP Server to expose A2A capabilities over the Model Context Protocol for compatibility with various hosts.

05Server Agent, a reference A2A agent implementation using Google ADK, LiteLLM, and Ollama.

06Agent Card Validation against the A2A protocol specification from URLs or local files.

Use Cases

01Testing and debugging custom AI agents that implement the A2A protocol.

02Exploring the capabilities of existing A2A agents quickly and efficiently.

03Enabling AI assistants to communicate with other agents through the MCP server bridge.