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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 v2.1.236

Old-style MCP tool-output rewrites from hooks are no longer applied silently

You'll notice
Useful3 Signal3
Hooks

A hook using only the older MCP output field no longer silently rewrites tool results.

updatedToolOutputupdatedMCPToolOutput
What

A PostToolUse hook that sets only the older updatedMCPToolOutput field, without the newer updatedToolOutput, no longer has its rewrite applied quietly; the result is marked as suppressed instead.

Details
  • Separately, MCP resource text is now run through a sanitizer before being handed to the model under "Full contents of resource:".
Evidence

u.legacyMcpRewriteSuppressed = !0;

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 v2.1.236 →