WebMCP: Give AI Agents Declared Tools Instead of a DOM to Scrape
WebMCP is an incubation-stage browser standard from the W3C Web Machine Learning Community Group, proposed by Google and Microsoft. Instead of scraping the DOM, a website registers its actions as structured tools with JSON Schema; an AI agent discovers them, calls them with typed arguments, and the page runs real JavaScript inside the user's already-open, authenticated tab. The author validates the pattern with a deployed demo, Career Copilot: it registers 13 WebMCP tools on a single page, and ChatGPT—which now supports WebMCP—used those tools in a real run, aggregating 75 live openings from GitLab, Stripe and Databricks, scoring 24 job descriptions, surfacing skill gaps, shortlisting 4 roles, then stopping for explicit human approval before submitting 3 applications. The post covers the minimal imperative API (one registerTool() call wrapping existing functions), the current Chrome 149 origin trial and flag, the call flow, and the trust model: same-origin restrictions, readOnlyHint / untrustedContentHint annotations, and human-in-the-loop confirmation for consequential actions. It also states limitations honestly: it is early, Chrome-first today, needs site adoption, and the security model is still maturing.