Amazon blocks Meta's AI agent, Walmart opens a gateway, and Sierra's $400 million book wins either way
Amazon blocked Meta's Muse in September and eBay has now restricted outside agents, while Walmart opened a gateway. Sierra co-writes the open protocol for agent access and also sells outcome-priced agents to the enterprises that may gate it, so its $400 million ARR book leans toward whichever way retailers decide.
Richard Tangtwo-minute read
The rules for how AI agents enter a business's website are being written this month, and Sierra~$10B — Sierra, private, latest valuation ~$10B, co-founded by Bret Taylor, the former Salesforce−0.10% — Salesforce, down 0.10 percent today co-CEO, is writing them while selling to both sides of the fight. Poppy, the Personal Agent Protocol that Sierra and Meta−0.87% — Meta, down 0.87 percent today announced with Shopify−1.29% — Shopify, down 1.29 percent today, Stripe, Walmart+0.16% — Walmart, up 0.16 percent today and others, gives agents a standard way to identify themselves at a business's digital door and lets the business set permissions, separate from commerce protocols that handle the purchase itself 1.
Taylor, in an interview published November 12, says who gets to roam is unsettled, and Poppy is how it gets settled 1.
The walls went up while agent traffic surged
Amazon+1.19% — Amazon, up 1.19 percent today blocked Meta's Muse personal agent in September and then shipped its own Alexa for Shopping agent, prototype to launch in four weeks 1. EBay restricted third-party agents in early November: Muse can no longer pull listings, and a spokesperson confirmed the company restricts agent access "in certain cases" 5.
Walmart went the other way, opening an Agent Gateway with per-customer agent profiles and spending limits 4. The reason both sides are moving now is speed: research from the venture firm Andreessen Horowitz, published November 10, found agentic browser traffic grew eightfold between August and October, with Muse driving about 60% of it 3. Retail sites now get a meaningful and rising share of visits from agent software, and someone has to answer them: either a door with rules, or a wall.
The pricing turns either outcome into Sierra revenue
Sierra's chief customer officer, Reggie Marable, said this month the company passed $400 million in annual recurring revenue, adding $150 million in the third quarter 2. The pricing model is the hinge: Sierra is paid only when its agent resolves a case with no human help; an escalation or a call-back means no payment 2.
Sierra's ARR climbed from $20M to $400M in about two years
Data
| ARR | |
|---|---|
| Oct 2024 | $20M |
| Nov 2025 | $100M |
| Mid 2026 | $200M |
| Q3 2026 | $400M |
If the open standard wins, personal agents like Muse reach businesses directly and Sierra supplies the agents answering inside those businesses, paid per resolution. If the walls win, enterprises buy Sierra's own agents to serve customers who arrive as machines. Either way the transaction runs through the same per-outcome book.
Three signals settle it, and the book leans to walls
Three signals will settle it: whether eBay−2.09% — eBay, down 2.09 percent today confirms and formalises the block, whether Amazon reverses under pressure from Muse's 10 million users 4, and which retailers sign Poppy beyond Walmart. On the evidence so far, Sierra's growth leans toward the walls scenario, since its revenue today comes from enterprises building their own agents rather than from the open protocol, and the protocol's payoff depends on adoption that has not happened yet.
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