The WebMCP Evaluation & Observability Platform
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Test your WebMCP implementation across:
• 1,000+ test cases
• 100+ LLMs
• 10+ languages
We are the first evaluation platform for WebMCP.
senro.ai
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Building WebMCP tools for @Meta AI glasses?
Our new guide covers how Meta AI discovers and calls WebMCP tools, schema and result handling, testing on desktop and glasses, Meta-specific limitations, and WebMCP vs. Meta AI Connectors.
Read it here:
senro.ai/blog/how-to-build-w…
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Meta has added WebMCP support to AI glasses.
WebMCP is now in developer preview for web apps on Meta AI glasses, letting developers define which actions Meta AI can trigger inside their apps.
Learn more from @MetaforDevs:
developers.meta.com/blog/met…
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Stripe has rolled out WebMCP across Stripe Checkout.
In Stripe’s evaluation, WebMCP-assisted agents:
• completed checkout 39% faster
• used 42% fewer tokens
• made 38% fewer tool calls
Learn more from @StripeDev:
stripe.dev/blog/how-stripe-i…
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WebMCP tools can now be marked as debugging-only.
Developers can identify tools intended for testing, inspection, or developer tooling so general-purpose agents can filter them out. This is available starting in Chrome 156.0.8067.0.
Check out this example by @quicksave2k:
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Microsoft Edge says its WebMCP implementation is ready for testing.
Developers can test WebMCP locally or through an origin trial, with samples and a browser extension for running and debugging WebMCP tools.
Learn more from @MSEdgeDev:
blogs.windows.com/msedgedev/…
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Vercel is bridging MCP and WebMCP.
mcp-handler now has experimental WebMCP support, letting developers expose selected existing MCP tools to in-browser agents by opting them in and adding a single script tag.
Learn more from @vercel_dev:
vercel.com/changelog/webmcp-…
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PayPal is bringing WebMCP to merchants.
In a small sandbox benchmark, @PayPal observed:
• ~2x faster median checkout
• ~4.6x lower model-inference usage costs
• 3 structured tool calls instead of 30+ interface interactions
Read more:
developer.paypal.com/communi…
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How does WebMCP work end to end?
Our complete guide covers the imperative and declarative APIs, tool schemas, annotations, lifecycle, discovery, execution, state, security, and a working example.
Read it here:
senro.ai/blog/how-webmcp-wor…
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🚨 Senro is open for beta testing this week!
We’re looking for developers working with WebMCP to try Senro and share feedback.
If you’re interested, DM us, comment below, or request access here:
senro.ai
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What’s the difference between WebMCP and MCP?
Our first Senro blog article explains what each one is, when to use them, and how they work together.
Read it here:
senro.ai/blog/webmcp-vs-mcp
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When WebMCP is standardized and broadly adopted, websites that don’t support it will fall behind because people will get used to co-browsing with agents.
Flight booking sites, e-commerce sites, hotel booking sites, and other transactional websites will feel the pressure first.
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⚠️ WebMCP API breaking change
Starting in Chrome 155.0.8052.0, 𝚎𝚡𝚎𝚌𝚞𝚝𝚎𝚃𝚘𝚘𝚕() now accepts an optional JavaScript object for input arguments instead of requiring a serialized JSON string.
François Beaufort (@quicksave2k) shared a backwards-compatible pattern:
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⚠️ WebMCP API breaking change
Starting in Chrome 155.0.8051.0, 𝚁𝚎𝚐𝚒𝚜𝚝𝚎𝚛𝚎𝚍𝚃𝚘𝚘𝚕.𝚒𝚗𝚙𝚞𝚝𝚂𝚌𝚑𝚎𝚖𝚊 returns a JavaScript object instead of a serialized JSON string.
François Beaufort (@quicksave2k) shared a backwards-compatible pattern:
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Want to understand how WebMCP works?
@kaskulikowski from Google covers how agents interact with websites, why semantic HTML matters, how WebMCP exposes structured tools, and how to implement, debug, and evaluate them.
Watch Kasper’s full presentation:
piped.video/HdCc-KezQPk
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WebMCP can now flag actions that may require human confirmation.
The new consequentialHint annotation lets tools signal high-stakes actions like booking a flight, transferring money, or deleting data.
Learn more in this article by @googledevs:
developer.chrome.com/docs/ai…
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Don’t confuse WebMCP for MCP.
WebMCP is for the frontend and lets browser agents interact with a live website, while MCP is for the backend and gives agents access to data and actions anywhere.
Learn more in this article from @googledevs:
developer.chrome.com/docs/ai…
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Every website will eventually have an interface for humans and an interface for AI agents.
WebMCP gives websites a native way to expose that agent interface.
Check out the WebMCP docs by @googledevs:
developer.chrome.com/docs/ai…
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Senro is offering free access to WebMCP Challenge participants.
If you’re building for the hackathon and want to test your WebMCP implementation before submitting, request access here:
senro.ai
The WebMCP Challenge is here.
We’ve teamed up with @ChromiumDev, @CloudflareDev, @ShopifyDevs, @vercel, @render, and @Netlify for a 10-day hackathon.
Up for grabs: $35,000 in cash prizes, Codex Micros, ChatGPT Pro subscriptions, and more prizes from our supporters.
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