San Francisco AI company Sierra on Friday released a draft of the Personal Agent Protocol, a proposed open standard for how AI assistants acting on someone's behalf should deal with businesses, and said 35 more companies have joined as design partners.

The new partners include OpenAI, Visa, Mastercard, PayPal, Venmo, Bank of America, Wells Fargo, Target, Nordstrom, Gap Inc., United Airlines, Cloudflare, Okta and Zapier, according to a post by Sierra co-founders Bret Taylor and Clay Bavor. Sierra first announced the project, nicknamed "Poppy," on Tuesday with Meta, Shopify, Stripe, Walmart, Rocket, Genesys and others.

The problem it tries to solve

Today, an AI agent that is asked to return a jacket or rebook a flight often has to log in as the customer and click through pages designed for people. Businesses usually can't tell an agent from a person, and they have no standard way to limit what it does. Sierra's pitch is that customers choose how much access to hand their agent, while companies set the boundaries of what agents may do.

How it would work

  • Discovery: a company posts a single file at a standard web address telling agents how to sign in and what they are allowed to do.
  • Sessions: an agent identifies itself and can start as a guest for simple questions, such as checking stock.
  • Sign-in: for account tasks the customer logs in through OAuth, and the agent gets a token limited to what the customer approved.
  • One visit across channels: the same session carries across a company's website, its APIs and its own customer-service agent.

The protocol leans on existing technology such as OAuth, JSON Web Tokens, OpenAPI and MCP, so developers can use tools they already have. In a demo at Sierra's conference this week, Rocket showed Meta's Muse agent getting a mortgage pre-approval through Rocket's own agent, with the user approving each step.

What isn't settled

Payments are listed as a future extension, not part of the first version, The Next Web reported, noting that Stripe and Shopify have also joined a rival agent standard backed by Visa. Sierra says it will hold design workshops and publish a reference implementation over the next month.

For Bay Area tech workers, the effort is another sign of where the AI money is heading: toward agents that carry out tasks, not just chat, and toward the plumbing that lets companies trust them.