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DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

← All of v2.1.239 Home All releases ←olderv2.1.238 v2.1.240newer→

Claude Code v2.1.239 21 Aug 2026

The word "mcp" in an argument no longer looks like the mcp subcommand

You'll notice

Useful3 Signal2

MCP

Passing the word "mcp" as an argument no longer makes Claude Code think it should run as an MCP server.

What

The check for whether Claude Code is running as an MCP server now asks which subcommand was actually parsed instead of scanning the raw command line for the word.

Details

An unrelated argument or file path containing "mcp" previously matched and suppressed a runtime override.

Evidence

process.argv.includes("mcp")

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.239 →