Websites can hand Codex their own tools

OpenAI has switched on WebMCP in the browser built into the ChatGPT desktop app and in ChatGPT Sites, letting a compatible website hand ChatGPT or Codex the tools required to finish a task. The rollout was announced by OpenAI's developer account on Twitter.

At a glance

• According to OpenAI, a compatible site exposes structured tools that agents can call directly, offering those actions alongside the interface people already use, instead of leaving the model to read the page.
• Visiting a compatible website is enough for the assistant to use it, and the only requirement on the user's side is running the latest version of the ChatGPT desktop app.
• The support spans two surfaces at once: the browser built into the ChatGPT desktop app and ChatGPT Sites, with the same automatic behaviour available to both ChatGPT and Codex on a compatible page.

Agent access to the web has so far meant reading pages designed for human eyes and simulating clicks on them. WebMCP inverts that arrangement: the site declares what an agent may do, and the agent calls those actions. For site operators the shift reads as a chance to define agent behaviour on their own terms, and it likely raises the question of which actions they are willing to expose in the first place.

OpenAI describes WebMCP as an experimental open standard that lets websites expose structured tools agents can use directly. In OpenAI's framing, a site publishes those actions next to the interface that people already work through, so the same page serves both a human visitor and a model.

Getting there takes one action: install the latest ChatGPT desktop app, then ask Codex to carry out the job on a site that supports the standard. The same built-in browser gained URL suggestions while typing in an earlier update of the app.

Alongside the rollout, OpenAI has opened a WebMCP Challenge, 10 days set aside for exploring what the standard can do in practice. The support in the desktop browser and in ChatGPT Sites, available to ChatGPT and Codex alike, was announced this week.

Which sites qualify

No list of websites implementing WebMCP has been published, and the feature only applies where a site carries the standard. OpenAI has not given a timeline for extending the support beyond the desktop app's browser and ChatGPT Sites, and the standard itself is still labelled experimental. The 10-day Challenge is the nearest fixed marker on the calendar.