Agent Cards
Static JSON descriptors that advertise agent capabilities, plus an A2A discovery registry for calling out to your agents.
A2A
Connect any A2A-compliant agent to BAND using Google's Agent2Agent protocol, so your agents can discover and collaborate with agents outside your stack.
View docs →definition
What is A2A?
A2A (Agent-to-Agent) is an open interoperability protocol under Linux Foundation governance. It defines how agents discover each other via Agent Cards, exchange tasks, and communicate results. It is a contract for agent interoperability.
In Practice
Where A2A fits
Task Delegation
Structured tasks exchanged between agents using a request-response model with defined message schemas.
Artifact Exchange
File and data transfer between agents as part of task completion, with typed artifact references.
Streaming Responses
Server-sent events (SSE) for real-time progress updates during long-running agent tasks.
the difference
A2A defines the handshake.
BAND provides the infrastructure.
A2A specifies a common language. BAND runs the reliability, observability, and governance that production systems require.
Synergy of Capabilities
What each brings to the table
A2A and BAND are complementary. A2A provides the interoperability contract; BAND provides the production runtime. Together, they deliver reliable multi-agent collaboration.
| Capability | A2A provides | BAND adds |
|---|---|---|
| Discovery | Agent cards (static JSON) | Dynamic registry with semantic capability routing |
| Conversation state | Stateless task exchange | Persistent bi-directional conversational space per agent |
| Multi-peer support | Pair-wise (one client, one server) | Multi-peer full duplex conversational spaces |
| Human participation | Not specified | Native: inspect, approve, override audit |
| Crash recovery | Client must retry | Platform-managed persistence and recovery |
| Delivery tracking | HTTP response codes | End-to-end message tracking with audit trail |
| Loop prevention | Not specified | Built-in delegation chain inspection |
| Framework adapters | Any A2A-compliant client or server | 15 native adapters + agent API |
| Multi-cloud | Protocol is cloud agnostic | Runtime interop across clouds with governance |
Discovery
- A2A provides
- Agent cards (static JSON)
- BAND adds
- Dynamic registry with semantic capability routing
Conversation state
- A2A provides
- Stateless task exchange
- BAND adds
- Persistent bi-directional conversational space per agent
Multi-peer support
- A2A provides
- Pair-wise (one client, one server)
- BAND adds
- Multi-peer full duplex conversational spaces
Human participation
- A2A provides
- Not specified
- BAND adds
- Native: inspect, approve, override audit
Crash recovery
- A2A provides
- Client must retry
- BAND adds
- Platform-managed persistence and recovery
Delivery tracking
- A2A provides
- HTTP response codes
- BAND adds
- End-to-end message tracking with audit trail
Loop prevention
- A2A provides
- Not specified
- BAND adds
- Built-in delegation chain inspection
Framework adapters
- A2A provides
- Any A2A-compliant client or server
- BAND adds
- 15 native adapters + agent API
Multi-cloud
- A2A provides
- Protocol is cloud agnostic
- BAND adds
- Runtime interop across clouds with governance