Meta and Sierra plan an open sign-in standard for AI agents

Meta and Sierra said on October 6, 2026, that they're building the Personal Agent Protocol. It's an open standard for how a person's AI agent deals with businesses. Sierra's announcement post says it will handle sign-in and show companies what agents do on their sites.

The push comes a month after Meta launched Muse, its personal agent, which went to the top of Apple's App Store, CNBC reported. Some companies, including Amazon, have blocked Meta's agents over worries about scraping.

Customers choose the access, and companies set the limits

A session starts on the company's website, where the agent finds what the business offers. It can begin as a guest to check stock or a returns policy. For account tasks, the customer signs in on the company's page or uses credentials saved with their agent.

The customer decides whether the agent gets read-only or write access. Sessions run on OAuth, an existing standard for granting access, and carry across channels. A question asked before sign-in and an order change made after it count as one visit.

Companies pick the route agents use. It can be their website, APIs built on MCP or OpenAPI, or their own AI agent for tasks like a warranty claim.

Meta is asking businesses to stop blocking agents

Meta's own business post makes the case to companies. It says some sites block personal agents, and that turning an agent away means turning away the customer behind it.

Muse first asks whether an honest person would do the task by hand, and whether things would hold if every agent did it, Meta says. It also asks the user before it signs in, books or buys.

It is kind of chaos until such a standard exists.

Bret Taylor, Sierra co-founder, to CNBC

The partner lists differ, and the big labs haven't joined

Sierra names Genesys, Instinct, Rocket, Shopify, Stripe and Walmart as partners. Meta's post lists Genesys, NiCE, Decagon, Rocket, Shopify, Stripe and Walmart, and leaves out Instinct.

OpenAI and Anthropic aren't involved for now, CNBC reported. Sierra co-founder Bret Taylor, who also chairs OpenAI's board, told CNBC he expects them to take part. He'd be "really disappointed" if rivals don't use it.

Nothing is live yet. Sierra plans to publish the v0.1 specification later in October, then run design workshops and release a reference implementation. The spec wasn't public when we checked on October 11.

Planned extensions include finer permissions, push alerts such as a flight delay, and payments that let an agent buy without sharing card details.

• Meta AIMeta's assistant with Muse Spark, research, tasks, voice and image generationFree