Personal Agent Protocol: Sierra and Meta Draft an Account-Access Standard for Consumer Agents
The Personal Agent Protocol, or Poppy, is a proposed open standard for how a consumer’s personal agent works with a company on that person’s behalf: how it finds the company, identifies itself, gets the user signed in with limited access, and then gets things done through the website, the company’s APIs, or the company’s own agent. Sierra and Meta announced it on 6 October 2026, and on 9 October Sierra published a draft specification and named 35 further design partners, including OpenAI, Visa, Mastercard, and PayPal. It is not a payment or checkout protocol. It fills a different gap, the one between “is this a legitimate agent?” and “may this agent act on this person’s account?”
What problem it addresses
The specification’s own framing is that agent access to companies is currently all or nothing: either the agent passes as the user, signing in with their password and clicking through pages built for people, or the company blocks it. Poppy proposes intermediate points. A company can let any agent browse, let signed-in agents see the user’s account, and require the user’s approval before an action with business effect; a user can let an agent read but not change.
How it works
- Discovery. A company publishes
/.well-known/poppy.json, describing how agents start sessions and sign in, and which APIs and company agent it offers. - Sessions and sign-in. The agent always identifies itself. Until the user signs in, the company sees only an opaque user ID that is stable over time but different at every company, so companies cannot match users with each other. Sign-in uses OAuth in three forms (on the company’s own page, on any device via a code, or mediated by the agent), and session tokens are bound to the agent’s key with DPoP.
- Channels. One session spans web browsing, APIs (described with OpenAPI or exposed as MCP tools), and conversations with the company’s agent, including handoff to a person.
- Operations extension. For actions with business effect, such as an exchange, a booking change, or a cancellation, the company proposes an operation with exact terms, the user approves that revision, and the agent confirms it once. The extension guarantees one record across channels and at-most-once execution. That is the part closest to commerce, and it is the protocol’s answer to “the agent did something I did not approve.”
Who is behind it
Sierra and Meta lead it. Launch partners named on 6 October include Genesys, Instinct, NiCE, Rocket, Shopify, Stripe, and Walmart; on 9 October Sierra added 35 more, among them OpenAI, Visa, Mastercard, PayPal, Venmo, Adyen, Plaid, Okta, Cloudflare, 1Password, Target, Nordstrom, Gap Inc., United Airlines, Bank of America, Wells Fargo, Chime, Synchrony, and BBVA. The spec site lists Meta, OpenAI, and Instinct as personal-agent design partners.
How to read it
Three cautions keep this in proportion.
- It is a fast-moving draft. Version 0.1 was published on 9 October under Apache 2.0. Version 0.2 was frozen fifteen days later, on 24 October, with most of its changes marked breaking, and a draft 0.3 is already in progress. The authors say compatibility promises start only at 1.0.
- No neutral governance yet. No foundation or standards body has been named. Compare MCP and A2A at the Agentic AI Foundation, x402 at the x402 Foundation, and AP2’s handover to the FIDO Alliance.
- Payments are explicitly out of scope for now. Payments, push notifications, and attachments are listed as open topics. Sierra calls Poppy complementary to UCP, and it has no stated relationship yet to ACP, AP2, Visa’s Trusted Agent Protocol, or Mastercard’s Agent Pay, even though both networks are design partners.
What makes it worth tracking is the partner list. OpenAI, members of UCP’s Shopping Tech Council (Shopify, Stripe, Target), both major card networks, and large US banks and retailers have all signed on to one account-access layer for consumer agents. Agent identity was already being worked on in at least five places (FIDO, the MCP roadmap, Rain’s Agentic Payments Alliance, EMVCo, and the Ant International, Mastercard, and Visa Know-Your-Agent collaboration). Poppy is a sixth, working one level up: not what the agent may spend, but what it may do on the person’s account. See the landscape and the timeline.