fx

Give Vercel’s fx coding agent a Kernel cloud browser via MCP

Overview

fx is Vercel Labs’ native CLI coding agent — a minimalist, terminal-first agent with a small built-in tool surface and first-class MCP support. Instead of loading every connected server’s full tool list up front, fx searches for the right capability on demand and only pulls in the tool it needs, which keeps context usage low even with several MCP servers connected.

Connecting Kernel’s MCP server gives fx a real cloud browser: it can create a session, drive it with Playwright via execute_playwright_code, and tear it down — the same toolset described in the MCP server reference, including managed auth, profiles, proxies, and replays.

For setup, follow the fx client guide — it covers both the interactive OAuth path and the API-key path needed for headless runs (fx ask, fx acp, CI).

Example

With Kernel connected, fx can drive a browser from a single prompt:

fx ask "Using the kernel MCP server, create a browser session, navigate to https://news.ycombinator.com, return the titles of the top 5 articles, then delete the session."

fx searches its connected servers for the right capability, calls manage_browsers to create the session, execute_playwright_code to scrape the titles, and manage_browsers again to delete it. A run looked like this (front page changes, so yours will differ):

1. AnkiDroid: Google Play no longer allowing Open Collective donation link
2. Ask HN: Who is hiring? (September 2026)
3. Urban Congestion Pricing and the Response Times of Emergency Medical Services
4. 44% on ARC-AGI-1 in 67 cents
5. Io_uring Without Readahead

Related

fx MCP client guide

Full setup steps, including headless auth

MCP Server

All tools the Kernel MCP server exposes

execute_playwright_code

Run Playwright against a session