--- title: "Standards and browser support" manual: "WebMCP tool for TYPO3" version: "0.4" permalink: "https://docs.typo3.org/permalink/neoblack/webmcp:standards@0.4" source: "Standards/Index.rst" rendered: "2026-10-07T22:31:54+00:00" --- > [!WARNING] > **Experimental.** This extension is experimental and not yet ready for > production use. It is built on top of > [WebMCP](https://github.com/webmachinelearning/webmcp), which is itself > an experimental, early-stage proposal. Both the underlying specification > and this extension's API may change or break at any time without notice. > Use at your own risk. # Standards and browser support {#standards} > [!IMPORTANT] > **Status as of 2026-10-07.** WebMCP moves fast. Everything on this page can > change without notice; check the linked sources before relying on it. > Statements are marked as *confirmed* (taken from a primary source) or > *unconfirmed*. - [The specification](https://docs.typo3.org/permalink/neoblack/webmcp:the-specification@0.4) - [Browsers](https://docs.typo3.org/permalink/neoblack/webmcp:browsers@0.4) - [Agents](https://docs.typo3.org/permalink/neoblack/webmcp:agents@0.4) - [What this means for site operators](https://docs.typo3.org/permalink/neoblack/webmcp:what-this-means-for-site-operators@0.4) - [Sources](https://docs.typo3.org/permalink/neoblack/webmcp:sources@0.4) ## The specification {#the-specification} - **Confirmed:** WebMCP is a *Draft Community Group Report* of the W3C Web Machine Learning Community Group (latest draft: 2 October 2026). It is **not** a W3C Standard and not on the W3C Standards Track. - **Confirmed:** the entry point is `document.modelContext`. Tools are registered one at a time with `registerTool(tool, { signal })` and unregistered by aborting that `AbortSignal`; there is no `unregisterTool()`. `provideContext()` and `clearContext()` were removed from the specification ([PR #132](https://github.com/webmachinelearning/webmcp/pull/132)). - **Confirmed:** tool annotations are `readOnlyHint`, `untrustedContentHint`, `consequentialHint` and `debugging` (all boolean). See [Writing tools](https://docs.typo3.org/permalink/neoblack/webmcp:developer@0.4) for how this extension sets them. - **Confirmed:** the declarative (HTML form) API is still a TODO in the specification; only a separate explainer exists. This extension does not use it. - **Confirmed:** open proposals may still change the API, among them renaming `execute` to `run` ([#158](https://github.com/webmachinelearning/webmcp/issues/158)) and returning the registered tool from `registerTool()` ([#234](https://github.com/webmachinelearning/webmcp/issues/234)). The runtime already accepts any return value of `registerTool()`. ## Browsers {#browsers} | Browser | Status | Confidence | | --- | --- | --- | | Chrome | Origin trial for desktop, milestones 149–156. Behind the flag `chrome://flags/#enable-webmcp-testing` for local testing. A default shipping milestone is **not set** on chromestatus. | Confirmed (shipping date unconfirmed) | | Microsoft Edge | Origin trial, expiring 2027-03-30. | Confirmed | | Brave | Experimental. | Unconfirmed | | Firefox | Mozilla standards position: *neutral*. | Confirmed (position label) | | Safari / WebKit | WebKit standards position: *oppose*. | Confirmed (position label) | There is **no cross-browser consensus**. Expect WebMCP to be available only in Chromium-based browsers, and only for some visitors, for the foreseeable future. > [!NOTE] > Chrome is reported to have deprecated `navigator.modelContext` in > favour of `document.modelContext` (Chrome 150). This could not be > confirmed from a Chrome source and is therefore *unconfirmed*. The > `@mcp-b/webmcp-polyfill` package still offers the navigator alias as > deprecated in version 5; its upcoming major no longer provides it. This > extension neither bundles nor requires a polyfill; see > [legacyNavigatorFallback](https://docs.typo3.org/permalink/neoblack/webmcp:confval-dataprocessor-legacynavigatorfallback@0.4). ## Agents {#agents} - **Confirmed:** the built-in browser of the ChatGPT desktop app uses WebMCP site tools. It only discovers tools of the top-level document (not iframes), runs a safety review per call and requires specific plans and models — see OpenAI's documentation below. - **Unconfirmed:** support in Gemini in Chrome has been announced but not confirmed by a primary source at the time of writing. ## What this means for site operators {#what-this-means-for-site-operators} - Treat WebMCP as **progressive enhancement**. Every page must work fully without it — most visitors' browsers do not offer the API. - The extension does nothing when the API is missing: no errors, no console output, no changes to the page. - Because the specification can still change, keep the extension up to date; until version 1.0.0 its API may change between minor versions. ## Sources {#sources} Primary sources: - [WebMCP specification draft](https://webmachinelearning.github.io/webmcp/) (W3C Web Machine Learning Community Group) - [webmcp issue #101](https://github.com/webmachinelearning/webmcp/issues/101) — `provideContext()` allows overwriting previously registered tools - [webmcp PR #132](https://github.com/webmachinelearning/webmcp/pull/132) — removal of `provideContext()` and `clearContext()` - [Chrome: Secure tools](https://developer.chrome.com/docs/ai/webmcp/secure-tools) (Google guidance, not part of the specification) - [Chrome Platform Status: WebMCP](https://chromestatus.com/feature/5117755740913664) - [Microsoft Edge origin trials](https://developer.microsoft.com/en-us/microsoft-edge/origin-trials/trials/0b76fe60-b266-458e-a285-04e375c0c31a) - [Mozilla standards position #1412](https://github.com/mozilla/standards-positions/issues/1412) - [WebKit standards position #670](https://github.com/WebKit/standards-positions/issues/670) - [OpenAI: WebMCP in ChatGPT](https://learn.chatgpt.com/docs/webmcp) - [OpenAI Help: Using site tools in the ChatGPT desktop app](https://help.openai.com/en/articles/20001423-using-site-tools-in-the-chatgpt-desktop-app) Secondary source (not independently confirmed): - [@mcp-b/webmcp-polyfill](https://www.npmjs.com/package/@mcp-b/webmcp-polyfill) package description and changelog of the related `@mcp-b` packages (navigator alias deprecation)