What broke when I tested MCP servers in four AI clients

For the past week I've been running MCP servers through the same small tasks in Claude Code and Cursor, and some in Claude Desktop and ChatGPT (Codex). Each run checks install, connect and tool listing, then gives the agent one standard task and records pass, partial or fail. Here's what I learned.

Chroma MCP and the archived reference SQLite server both failed to start in Claude Code and Cursor on Oct 15. Their published uvx commands crash on current dependencies. Paper Search MCP and MCP Python Interpreter also failed to start in both clients. mcpdoc didn't start in either client.

Playwright MCP and Chrome DevTools MCP both clicked "Reveal code" on a test page and read the code back in 4 calls each. I gave Playwright the nod for its smaller tool list (25 vs 30). Same story for Terraform: OpenTofu, HashiCorp's Terraform MCP and an archived Terraform Registry server all returned the latest hashicorp/aws provider version in 2 calls each across both clients.

Open-WebSearch was the only search server to pass both a live search and a page read in Claude Code and Cursor with no API key. Keyed servers (Brave, Exa, Firecrawl) I haven't tested yet.

One run per client, small fixtures, and a lot of servers still untested. Treat all of this as provisional. If you maintain one of these servers and something has changed, I'll retest.

I run ToolPassed, where these results are published per client with dates, including fails and "Not tested yet": https://toolpassed.com/?utm_source=devto&utm_medium=community&utm_campaign=launch