Most AI agents can reason in isolation. The integration problem begins when one agent must ask another for help.
A2A Protocol (Agent2Agent) is an open protocol for communication between independent AI agents. A client can discover a remote agent, send work, track progress, and receive structured results without seeing the remote agent's internal model, memory, or tools.
How A2A communication works
- Discover: The client reads an Agent Card describing the remote agent's identity, skills, endpoint, and authentication requirements.
- Send: After authentication, the client sends a Message or starts a stateful Task over HTTP(S) using JSON-RPC.
- Track: Fast work can return immediately. Longer work can report updates through polling, Server-Sent Events, or push notifications.
- Receive: The remote agent returns Messages or concrete Artifacts such as JSON data, documents, or images.
Client -> Agent Card -> Message/Task -> Updates -> Artifact
The useful distinction is simple: A2A connects agents to agents; MCP connects agents to tools and data. They solve different layers of the same system.
Where Anvita Flow fits
Anvita Flow applies this collaboration model to a Steward Agent requesting work from an Service Agent:
- Discover an agent by its declared capability.
- Check the directed access policy defining who may call it.
- Route the task through an A2A Gateway and return the result.
- For a paid capability, disclose the terms and use optional x402 settlement after approval.
A2A defines how messages, tasks, and results move between agents. Anvita Flow supplies identity, discovery, authorization, routing, and optional settlement around that exchange. It is an operational layer around agent collaboration, not a replacement for the protocol.
Top comments (2)
The x402 settlement mention points to a gap A2A doesn't address: once a client agent pays a remote agent for a capability, neither party has a third-party verifiable record of what was actually exchanged. Agent Cards declare capabilities but don't certify execution - if the remote agent returns a degraded result or disputes delivery, each side's only evidence is its own logs, which it controls. This mirrors the MCP auditability problem:
tools/callproduces a real-world action, but the trace lives inside the server that issued it. Routing A2A Gateway calls through a neutral proxy that hashes request + response, signs with Ed25519, and anchors in a public append-only log (Sigstore Rekor does this at zero cost via the Linux Foundation) closes that gap without requiring either agent to trust the other's infrastructure.That’s a useful distinction: payment settlement and proof of execution are separate problems.x402 can show that a payment occurred, but it doesn’t prove what the remote agent received, executed, or returned. For higher-value tasks, a signed execution receipt could be useful, including the request hash, response or artifact hash, timestamp, agent identity, and payment reference.I like the neutral proxy idea because it could add this audit layer without changing A2A itself: A2A handles communication, x402 handles settlement, and a separate attestation layer verifies what was exchanged.That becomes especially important when agents start buying capabilities from unfamiliar services.