Lesson 1 · 12 min
WebMCP lets a page hand tools to an agent in the browser. As of Oct 19, 2026, it is a Community Group draft, tested in an origin trial in Chrome and Edge, with Mozilla neutral and WebKit opposed. In this lesson you check the spec date with one command and learn to read the status without falling for a promise.
Start the lesson
Goal: place WebMCP as of Oct 16, 2026 (CG draft, origin trial 149–156, local flag, backers and objections) and check the spec date with a command.
Click each step.
A draft with a date, a trial with a deadline, and no stable date: that is why the course teaches you to prepare the page with detection and fallback.
Four questions, always with a date.
A Community Group spec is a draft from an open group. It is not a W3C standard.
Read the spec's subtitle: the type and the date are at the top.
Draft Community Group Report, 16 October 2026.
An origin trial works for one domain with a token and has a set end date. A flag only works on your machine.
Neither one reaches the average visitor without you doing something.
Origin trial 149–156; flag #enable-webmcp-testing for localhost.
Standards positions tell you whether another engine plans to implement it.
WebKit opposed it, citing API design, duplication, i18n, portability, privacy, and security.
Mozilla #1412: neutral (Aug 3, 2026). WebKit #670: oppose.
The surface name, the declarative API, annotations, exposedTo, and the return shape can change.
Keep the spec date in your code, like the comment in the kit.
navigator.modelContext → document.modelContext (PR #177, May 19, 2026).
It downloads the spec, strips the tags, and counts. If the date is different, the spec changed: reread what changed before you continue the course.
curl -s https://webmachinelearning.github.io/webmcp/ | sed 's/<[^>]*>//g' > /tmp/webmcp-spec.txt tr -s ' \n' ' ' < /tmp/webmcp-spec.txt | grep -o "Draft Community Group Report, [0-9]* [A-Z][a-z]* [0-9]*" | head -1 echo "document.modelContext: $(grep -c 'document.modelContext' /tmp/webmcp-spec.txt) linhas" echo "navigator.modelContext: $(grep -c 'navigator.modelContext' /tmp/webmcp-spec.txt) linhas" echo "unregisterTool: $(grep -c 'unregisterTool' /tmp/webmcp-spec.txt) linhas"
Draft Community Group Report, 16 October 2026 document.modelContext: 16 linhas navigator.modelContext: 0 linhas unregisterTool: 0 linhas
16 lines mention document.modelContext; none mention navigator.modelContext or unregisterTool. To remove a tool, the spec uses the signal of an AbortController (lesson 4).
A tutorial that uses navigator.modelContext, unregisterTool, provideContext, or clearContext predates May 2026 (the switch to document happened on 05/19/2026): none of those names exist in the 10/16/2026 spec. The same count above (0 lines) is your test before you copy code from a blog.
No installs beyond curl. Each exercise ends with a done when.
Run the spec block and write the date at the top of your tools file, like the comment in kit/pagina/ferramentas.mjs.
Done when: The block (pasted into the terminal) prints Draft Community Group Report, 16 October 2026 and navigator.modelContext: 0 linhas. A different date = a new spec: note what changed.
Open Chrome Status (entry 5117755740913664) and the positions from Mozilla (#1412) and WebKit (#670). Write three lines: stage, browsers, and positions, each with the date you read it.
Done when: You have a status-webmcp.md file with three dated lines, and none of them says "standard" or "works in every browser".
The explanation appears after your answer.
Question 1 of 4
What is the WebMCP document from 10/16/2026?
Question 2 of 4
You want to test WebMCP on localhost today. What turns it on?
Question 3 of 4
Which of these names still exists in the 10/16/2026 spec?
Question 4 of 4
Why does the course use feature detection and a fallback in every example?
Pick an answer. The explanation shows up after you try.