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Sweep 22 Oct 2026 · 21:04Z Build v2.1.309 528 read Stable v2.1.308 Latest v2.1.309 Next v2.1.309 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.221 ·

MCP connection-failure telemetry normalizes the error code

MCP failure codes are now cleaned up before reporting, so odd server values don't leak through.

Under the hood Internal Changes
JSON All of v2.1.221
Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
0Signal: worth watching, 1 to 5
MCPArea: what it touches
Internal ChangesKind: in v2.1.221,
Internal ChangesSection of the release
What

The error code attached to MCP connection failures is now classified before being reported, so arbitrary values from a server do not reach telemetry verbatim.

Details
  • Emits missing when there is no code, the numeric value when it is an integer, a known code from an allow-list, or other as the fallback.
  • Applies to every tengu_mcp_server_connection_failed report; no gate.
Evidence

tengu_mcp_server_connection_failed

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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