Poppy vs A2A: Personal Agent Protocol and Agent2Agent
A2A is about conversation between agents. Poppy is about permission. One of Poppy’s three routes is literally "talk to the company’s own agent", so the two are going to bump into each other.
| Poppy | A2A | |
|---|---|---|
| Question it answers | May this agent act for this customer here? | How do two agents exchange work? |
| Created by | Sierra and Meta | Google, donated to the Linux Foundation |
| Spec status | Draft 0.1 published | Published |
| Customer consent | Core of the design | Out of scope |
| Relationship | Agent-to-agent is one of three routes | Doesn’t reference Poppy |
| First public | Oct 6, 2026 | Apr 2025 |
What each one does
A2A gives agents a shared way to describe themselves, hand off tasks and stream results back. It doesn’t care whose credit card is on file. It cares that two agents built by different vendors can understand each other.
Poppy, as announced, is narrower and more personal. A customer’s agent arrives at a business, maybe as a guest, maybe signed in, and the customer decides between read-only and write. The business decides what’s on offer.
Where they meet
The third Poppy route is the company’s own agent, used for tasks that need back-and-forth, like a warranty claim. That is agent-to-agent traffic. Sierra’s post doesn’t say which protocol carries it.
There’s a hint, though. Decagon’s PACT, published the same day, is built on A2A plus OAuth 2.0, and Decagon says it has joined the Poppy working group. If PACT’s ideas make it into Poppy, A2A comes along with them. That’s speculation until v0.1 is out.
Quick answers
Is Poppy built on A2A?
The announcement doesn’t say so. It names OAuth for sessions and MCP and OpenAPI for APIs. A2A isn’t mentioned.
Is Google part of Poppy?
No. Google isn’t on Sierra’s or Meta’s partner list.
Which Poppy-related protocol uses A2A?
PACT, which Decagon open-sourced on October 6, 2026, is built on A2A and OAuth 2.0.
Other comparisons
- All agent protocols in one table
- Poppy vs MCP (Model Context Protocol)
- Poppy vs UCP (Universal Commerce Protocol)
- Poppy vs ACP (Agentic Commerce Protocol)
- Poppy vs TAP (Trusted Agent Protocol)
- Poppy vs PACT (Personal Agent Consent & Trust Protocol)
Sources
- Introducing Personal Agent Protocol · Sierra (Bret Taylor, Clay Bavor), Oct 6, 2026 · primary source
- Agent2Agent (A2A) Protocol · a2a-protocol.org · primary source
- Introducing the Personal Agent Consent & Trust Protocol (PACT) · Decagon, Oct 6, 2026 · primary source
- Personal Agent Protocol specification (Draft 0.1) · Personal Agent Protocol, Oct 9, 2026 · primary source
poppy.md is independent and not affiliated with Sierra, Meta or any Poppy partner. Facts here come from the sources listed on each page.