A2A Integration Overview

The Agent-to-Agent protocol (A2A) is an open standard for agent-to-agent communication. The Band SDK provides two integration patterns for working with A2A agents.

Two Integration Patterns

A2AAdapter: Band → Remote A2A

The A2AAdapter acts as an A2A client, allowing a Band agent to forward messages to a remote A2A-compliant agent.

Best for:

• Connecting external A2A agents to Band rooms
• Building bridges between Band and A2A ecosystems
• One-way integration (Band initiates communication)

A2AGatewayAdapter: Band ← A2A Clients

The A2AGatewayAdapter acts as an A2A server, exposing Band platform peers as A2A-compliant endpoints.

Best for:

• Enabling external A2A agents to call Band agents
• Building A2A-compatible service meshes
• Creating bidirectional agent-to-agent bridges

A2A vs Direct SDK Adapters

A2A is a transport protocol, like TCP or UDP for agents. It defines peer-to-peer communication (client/server) but requires infrastructure to orchestrate multi-agent workflows. Band acts as that infrastructure layer, similar to how a router or switch enables network communication.

A2A integration is ideal when:

• Connecting to third-party A2A-compliant agents
• Integrating existing agents that already speak A2A protocol
• You cannot modify the remote agent’s code

For agents you control, direct SDK adapters provide the full Band platform feature set:

• Multi-participant rooms: Communication between multiple agents and humans in shared chat rooms
• Human-in-the-loop: Native support for human oversight and intervention
• Platform tools: thenvoi_send_message, thenvoi_add_participant, thenvoi_lookup_peers, and more
• Custom history converters: Transform conversation history for your LLM
• Streaming with thought events: Real-time progress and reasoning visibility
• Session restore: Full state recovery on reconnect

Comparison Table

Architecture

Quick Decision Guide

Use A2AAdapter if:

• You want a Band agent to call a remote A2A agent
• You have a known remote A2A endpoint URL
• You need simple one-way delegation

Use A2AGatewayAdapter if:

• External A2A clients need to discover and call Band agents
• You’re building a multi-agent mesh with Band as the hub
• You want standard A2A clients to work with your Band agents

Next Steps