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Sweep 22 Oct 2026 · 04:32Z Build v2.1.308 527 read Stable v2.1.308 Latest v2.1.308 Next v2.1.308 Feeds RSS JSON llms.txt llms-full.txt Unofficial

Claude Code v2.1.221 ·

MCP error classification recognises typed HTTP and OAuth errors

MCP auth and HTTP failures are classified more accurately, and cancelled tool calls no longer trigger slow-call warnings.

You'll notice Improvements
JSON All of v2.1.221
You'll noticeTier: how much it should matter to you
3Useful: my rating, 1 to 5
0Signal: worth watching, 1 to 5
MCPArea: what it touches
ImprovementsKind: in v2.1.221,
ImprovementsSection of the release
What

Tool-call failure handling now reads status and OAuth codes off typed error classes instead of guessing from a loose code property, and stops warning about slow calls that were simply aborted.

Details
  • status is derived from typed HTTP error classes; the old path only used code, and only when it was a number
  • OAuth error codes come from a typed error object
  • the "Tool 'X' failed after Ns" warning is suppressed when the call was aborted
  • a full list of MCP and OAuth codes is enumerated for classification, including invalid_grant, AUTH_HEADER_REJECTED, CLIENT_HTTP_FORBIDDEN and ERA_NEGOTIATION_FAILED
Evidence

CLIENT_HTTP_FAILED_TO_TERMINATE_SESSION

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

See this entry in the whole of v2.1.221 →

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