Short answer: WebMCP is an early, still-changing proposal that lets a web page tell an AI agent running in the browser which actions it offers, as named tools with input schemas. Mathify supports it in a small way: on pages where the browser provides the feature, it registers tools for searching calculators, opening one, and running the calculator on the current page. In browsers without the feature, nothing happens.

What problem does WebMCP solve?

Today an AI agent that uses a website usually works like a person would. It reads the page, guesses which button does what, clicks and types. That is slow and brittle, because a small change in the layout can break it.

WebMCP takes a different approach. The page declares: "here are the things I can do, here are their inputs". An agent can then call a tool directly instead of imitating mouse clicks. The same idea underlies MCP servers, but the tools live in the open page rather than on a remote server.

How is WebMCP different from regular MCP?

The two share a vocabulary (tools, descriptions, JSON Schema inputs) but run in different places:

Where it runs. A normal MCP server is a remote service your assistant connects to by URL. WebMCP tools exist inside a web page and are available only while that page is open in the browser.
Who calls it. WebMCP is meant for an agent that lives in or alongside the browser, such as a built-in assistant. A server connection is made by the assistant application.
State. An MCP server like Mathify's is stateless. A WebMCP tool can act on the page you are looking at, for instance by navigating to another page.

Neither replaces the other. If you want any assistant to run a Mathify calculation from anywhere, the MCP connection guide is the relevant route.

What is the status of WebMCP?

It is early. The idea is being developed as a browser proposal, its API surface has changed during that development, and support is limited to certain browsers and builds. We will not name versions or dates here, because that kind of detail goes out of date quickly. Check the current specification and your browser's release notes before relying on it.

One detail of the changing surface is visible in Mathify's code. Early builds exposed the entry point on the navigator object, and current Chrome builds put it on document (document.modelContext). Mathify uses the document location only, and treats the older navigator location as deprecated. Because this is a moving preview, check the current draft before relying on either name. If the feature is not present, the registration code does nothing and no error is shown.

What does Mathify register?

There are two layers.

Site-wide tools, from the main site layout. Two tools are registered once per page load:

search_calculators takes a query and returns matching calculator names, categories and page URLs. It searches an index in the browser and does not navigate.
open_calculator takes a calculator path such as /finance/mortgage and navigates the current tab to that calculator. It only accepts paths that exist in Mathify's own index, and it rejects anything that does not start with a single slash.

A calculator tool, on supported calculator pages. A calculator page that has an agent adapter registers one more tool describing that calculator and its inputs. When an agent calls it, the calculation runs in the page using the same code that produces results for other callers. The result comes back as the answer plus a link to the page with the inputs prefilled.

Two details about behaviour:

Errors are flagged as errors. If a call fails, the response is marked as an error instead of returning a message that looks like a result, so an agent does not mistake a failure for an answer.
Tools are removed when you leave the page. Registration is tied to the page being mounted, so tools do not linger after navigation.

How is this different from the public API?

The calculation code is the same. The delivery is different. The MCP and REST endpoints run on Mathify's servers and work for any client. WebMCP tools run in your open tab, so the calculation for a calculator tool happens in the browser. Search also runs in the browser, using an index that is loaded only when an agent actually calls the tool.

Will this change what I see as a visitor?

No. The registration components render nothing. If you use a browser or agent that supports WebMCP, an agent can discover and call the tools. If you do not, the pages look and work exactly the same.

Common mistakes and misunderstandings

Assuming every browser supports it. It does not, and the proposal may change.
Confusing WebMCP with a hosted MCP server. WebMCP tools exist only while the page is open.
Treating tools as permissions. A tool is a described action, not a security boundary. Only expose actions that are safe to call.
Expecting a count of supported pages. Which calculator pages register a tool depends on whether they have an adapter, and that set grows over time.

Key takeaways

WebMCP lets a page publish tools for in-browser AI agents. It is early and its details may change.
Mathify registers a search tool and an open tool from its main site layout, plus a calculator tool on supported pages.
It checks that the feature exists before registering anything, and does nothing when it is absent.
For use from any assistant, the hosted MCP server and REST API remain the main options.

FAQ

Do I need to enable anything to use WebMCP on Mathify?

No setting on Mathify's side. Whether an agent can see the tools depends on your browser or agent supporting WebMCP and on its own settings.

Does WebMCP send my numbers to Mathify?

A WebMCP calculator tool runs in your page, so the calculation itself happens in the browser. If the agent is a cloud service, the question you ask it still goes to that service under its own terms.

Is WebMCP a web standard?

It is an early proposal, not a finished standard. Treat the details as subject to change.

Which Mathify calculators have a WebMCP tool?

Those whose pages have an agent adapter. That list is growing, so there is no fixed number to quote. Calculators without one are still reachable through the site-wide search and open tools.

Where can I try a calculator that an agent can use?

Any calculator page is a start, such as the Percentage Calculator or the Mortgage Calculator. Whether an agent can call it depends on your browser and agent.

What Is WebMCP and How Does Mathify Use It?