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MCP-B: A Protocol for AI Browser Automation

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Re: MCP-B: A Protocol for AI Browser Automation

#2
Hey HN,

This was an idea I had while trying to build MCP servers internally at Amazon. Today I am open sourcing it. TLDR it's an extension of the Model Context Protocol which allows you to treat your website as an MCP server which can be discovered and called by MCP-B compliant web extensions.

You can read a more detailed and breakdown here (with gifs): https://mcp-b.ai/blogs

Re: MCP-B: A Protocol for AI Browser Automation

#3

Hey HN, This was an idea I had while trying to build MCP servers internally at Amazon. Today I am open sourcing it. TLDR it's an extension of the Model Context Protocol which allows you to treat your website as an MCP server which can be discovered and called by MCP-B compliant web extensions. You can read a more detailed and breakdown here (with gifs): https://mcp-b.ai/blogs

Oh and the code is here: https://github.com/MiguelsPizza/WebMCP

Re: MCP-B: A Protocol for AI Browser Automation

#5

Would it be possible to do this with any arbitrary website since we can execute JS client side?

Yup! You just declare a standard MCP server and attach a TabServerTransport to it. Any TabClientTransport in the same Tab will be able to connect to it.

The examples focus mostly on extensions injecting clients at website load time, but you can ship a client with your server javascript. That being said, if the client and server live in the the same script I recommend just using the InMemoryTransports from the official SDK.

Re: MCP-B: A Protocol for AI Browser Automation

#7

I don't get it from the homepage, feels like Selenium on the browser, since you built it can you explain ?

Similar but also very different. Playwright and Selenium are browser automation frameworks. There is a Playwright-MCP server which let's your agent use Playwright for browser automation.

MCP-B is a different approach. Website owners create MCP servers `inside` their websites, and MCP-B clients are either injected by browser extensions or included in the websites JS.

Instead of visual parsing like Playwright, you get standard deterministic function calls.

You can see the blog post for code examples: https://mcp-b.ai/blogs

Re: MCP-B: A Protocol for AI Browser Automation

#10

I don't get it from the homepage, feels like Selenium on the browser, since you built it can you explain ?

Similar but also very different. Playwright and Selenium are browser automation frameworks. There is a Playwright-MCP server which let's your agent use Playwright for browser automation. MCP-B is a different approach. Website owners create MCP servers `inside` their websites, and MCP-B clients are either injected by browser extensions or included in the websites JS. Instead of visual parsing like Playwright, you get…

What differentiates this from something like data-test-id attributes?
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