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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 v2.1.248

MCP server allow and deny lists get settings keys

Use it now
Useful4 Signal4
MCP Notable

You can allow or block specific MCP servers with allowedMcpServers and deniedMcpServers settings.

allowedMcpServersdeniedMcpServers
What

Two settings keys, allowedMcpServers and deniedMcpServers, are now paired with validation schemas in a table, so MCP servers can be permitted or blocked from settings files.

Details
  • New arrays group the settings tiers: policySettings, flagSettings and userSettings on one side, localSettings and projectSettings on the other, with a map labelling the first three policy, flag and user.
  • A separate map ties the decisions allow, deny and ask to the rule lists alwaysAllowRules, alwaysDenyRules and alwaysAskRules.
Evidence

{ key: "allowedMcpServers", schema: tzt }

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 v2.1.248 →