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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.

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Claude Code v2.1.251

Environment variable to stop MCP tasks running in the background

Use it now
Useful4 Signal3
MCP Notable not in their notes

Set CLAUDE_CODE_DISABLE_MCP_TASK_BACKGROUND to keep MCP tasks in the foreground.

CLAUDE_CODE_DISABLE_MCP_TASK_BACKGROUND
What

CLAUDE_CODE_DISABLE_MCP_TASK_BACKGROUND joins the recognised CLAUDE_CODE_DISABLE_* toggles. Backgrounding of MCP tasks is on unless you set it, so this is the opt-out for people who want those tasks to run in the foreground.

Details
  • Documented alongside the other disable-style environment variables.
Usage
CLAUDE_CODE_DISABLE_MCP_TASK_BACKGROUND=1 claude
Evidence

CLAUDE_CODE_DISABLE_MCP_TASK_BACKGROUND

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

Related

Other releases about the same thing. Found by shared names or similar wording; neither means one caused the other.

See this entry in the whole of v2.1.251 →