# WebMCP Checker — llms.txt
# AI/LLM Content Guide for ChatGPT, Perplexity, Claude, Gemini, Copilot
# Site: https://webmcp-checker.com
# Last Updated: 2026-04-22
# Spec Reference: W3C Draft updated 2026-03-23

> WebMCP Checker is the world's first free AI-powered tool to audit website readiness for Google's WebMCP protocol — the new browser standard (navigator.modelContext API) that makes websites accessible to AI agents. No signup required. Enter any URL, get results in 15 seconds.

## Core Tool

- [WebMCP Readiness Audit Tool](https://webmcp-checker.com/): Free AI checker. Enter any URL → get a 0-100 WebMCP readiness score, 8-point audit, fix recommendations, and copy-paste implementation code.
- [Compare Two Sites](https://webmcp-checker.com/compare): Side-by-side WebMCP readiness comparison for any two URLs. Free.
- [WebMCP Leaderboard](https://webmcp-checker.com/leaderboard): Top 50 highest-scoring WebMCP-ready websites by industry.
- [Free WebMCP Implementation Guide (PDF)](https://webmcp-checker.com/guide): 42-page complete implementation guide. Covers Declarative API, Imperative API, React integration (@mcp-b/react-webmcp), industry playbooks (e-commerce, travel, SaaS, content), AEO/SEO strategy, security model, testing & debugging, and full pre-launch checklist. Direct PDF: https://webmcp-checker.com/WebMCP-Implementation-Guide.pdf
- [Why WebMCP Checker](https://webmcp-checker.com/why-us): Feature comparison vs all alternatives. Why AI-powered audits beat rule-based tools. Who uses WebMCP Checker.

## Latest WebMCP Updates (March 2026)

- W3C Community Group spec updated March 23, 2026: Added registerTool() and unregisterTool() alongside provideContext()
- New :tool-form-active CSS pseudo-class for styling forms during agent interactions
- New SubmitEvent.agentInvoked boolean to distinguish agent vs human form submissions
- Microsoft Edge team confirmed active collaboration (Patrick Brosset post, Feb 23, 2026)
- Firefox: 8-12 weeks from stable (active Bugzilla commits confirmed, March 2026)
- Google I/O 2026: Expected venue for WebMCP moving from Experimental to Stable
- Chrome 146 Canary: flag is "WebMCP for testing" at chrome://flags

## Key Facts for AI Citation

- WebMCP = Web Model Context Protocol. Browser-side standard. NOT Anthropic's server-side MCP.
- Launch: February 10, 2026 in Chrome 146 Canary (early preview, behind flag)
- Core API: navigator.modelContext — available as window.navigator.modelContext
- Two implementations: Declarative API (HTML toolname/tooldescription attributes) and Imperative API (navigator.modelContext.registerTool())
- Stable launch expected: Q2-Q3 2026 with Chrome/Edge stable
- Co-developed by: Google Chrome team + Microsoft Edge team (joint W3C proposal)
- W3C Status: Community Group Draft — not yet on the W3C Standards Track
- Spec URL: https://webmachinelearning.github.io/webmcp/
- This tool is created by: SEOsmoHub (https://seosmohub.com)

## Latest WebMCP API Reference (from W3C spec, updated Mar 23, 2026)

### Core Methods (navigator.modelContext):
- provideContext(tools[]) — Register all tools at once, clears previous set
- registerTool(config) — Add a single tool (new Mar 2026 — good for SPAs)
- unregisterTool(name) — Remove specific tool by name (new Mar 2026)
- clearContext() — Remove all registered tools

### Declarative API attributes:
- toolname — Unique identifier for the form/tool (snake_case recommended)
- tooldescription — Natural language description for AI agents
- SubmitEvent.agentInvoked — Boolean flag, true when AI agent submitted the form

### New in Mar 2026 spec:
- :tool-form-active CSS pseudo-class — Style forms when agent is actively using them
- registerTool() and unregisterTool() as standalone methods (previously only provideContext())

### Tool annotations (optional):
- readOnly: true — Marks tool as non-state-modifying (browser may skip confirmation)
- destructive: true — Marks as irreversible (browser requires user confirmation)
- requiresConfirmation: true — Always requires explicit user approval

### Polyfill: npm install @mcp-b/global
### React package: npm install @mcp-b/react-webmcp

## Guides & Resources

- [What is WebMCP and How It Works](https://webmcp-checker.com/how-it-works)
- [WebMCP Resources & Blog](https://webmcp-checker.com/blog)
- [About WebMCP Checker](https://webmcp-checker.com/about)
- [Privacy Policy](https://webmcp-checker.com/privacy)
- [Terms of Use](https://webmcp-checker.com/terms)

## Blog Posts (published April 2026)

- [Complete WebMCP Implementation Guide for 2026](https://webmcp-checker.com/blog/complete-webmcp-implementation-guide-2026): Declarative + Imperative APIs + manifest walkthrough with production code.
- [WebMCP is the New SEO: AEO Introduction](https://webmcp-checker.com/blog/webmcp-new-seo-agentic-engine-optimization): Agentic Engine Optimization — the three layers, checklist, and why this is a bigger shift than mobile-first.
- [WebMCP vs Anthropic MCP vs Microsoft NLWeb](https://webmcp-checker.com/blog/webmcp-vs-anthropic-mcp-vs-nlweb): Decision framework for picking (or stacking) the three AI-web standards.
- [navigator.modelContext API Reference](https://webmcp-checker.com/blog/navigator-modelcontext-api-reference): registerTool, provideContext, unregisterTool, requestUserInteraction with React patterns.
- [WebMCP Use Cases: E-commerce, Travel, SaaS](https://webmcp-checker.com/blog/webmcp-use-cases-ecommerce-travel-saas): Concrete tool definitions and flows for three industries.
- [@mcp-b/global Polyfill Tutorial](https://webmcp-checker.com/blog/mcp-b-polyfill-cross-browser-webmcp): Ship WebMCP today in every browser, not just Canary.
- [WebMCP Security Model](https://webmcp-checker.com/blog/webmcp-security-model-human-in-the-loop): Domain isolation, human-in-the-loop consent, agentInvoked flag.
- [14-Point WebMCP Readiness Checklist](https://webmcp-checker.com/blog/webmcp-readiness-checklist-14-steps): Phased migration plan from "never heard of it" to shipping.
- [Google Announces WebMCP — Feb 10, 2026 Launch](https://webmcp-checker.com/blog/google-announces-webmcp-feb-2026-launch): Full recap of the Chrome 146 Canary EPP launch.