What was going on
Wired up the Browserbase MCP server in Claude Desktop and every tool call dies with: "Failed to initialize/reinitialize Stagehand: You seem to be calling `page` on a page in an uninitialized `Stagehand` object. Ensure you are running `await stagehand.init()` on the Stagehand object before referencing the `page` object." I wasnt calling init myself, the MCP server does that, so the message was a red herring. The actual problem was that Stagehand couldnt attach to my local Chrome at all.
What fixed it
Starting with Chrome 136, `--remote-debugging-port` no longer works unless you also pass a custom `--user-data-dir`. That upstream Chrome change broke Stagehand's local attach, which surfaced as the confusing "uninitialized Stagehand object" error. Launch Chrome with both flags, e.g. `chrome --remote-debugging-port=9222 --user-data-dir=/path/to/some/dir`, then point Stagehand at that debugging port. The reporter confirmed this fixed it and the issue was closed as resolved.