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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 v2.1.290 ·

Failed MCP connections now record the proxy's status code and skip retries on proxy 403

MCP connections that fail at a proxy now keep the proxy's HTTP status as proxyConnectStatus, and a 403 there no longer triggers an automatic reconnect

Group of 3 You'll notice Internal Changes
JSON All of v2.1.290
You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
TelemetryArea: what it touches
Internal ChangesKind: in v2.1.290,
ImprovementsSection of the release

Unclear Whether the new report on the first tool list is sent every time or only for some sessions is not clear.

What

MCP servers are outside programs that give Claude Code extra tools. Some networks reach them through a proxy, a middleman server that passes traffic on. When an MCP connection fails because the proxy refused to open a tunnel (error ERR_PROXY_TUNNEL), the failure record now includes proxyConnectStatus. This is the numeric HTTP status code the proxy sent back. Before, the record held only the name, type, config, error and error code.

  • If proxyConnectStatus is 403, meaning the proxy forbids the connection, Claude Code no longer treats the failure as worth retrying automatically.
  • Connection success and failure records now include processUptimeAtConnectStartMs, how long Claude Code had been running when the connection attempt began.
  • A new diagnostic record is written after the first list of tools comes back from a server.
  • The connection-timeout retry switch tengu_mcp_connect_timeout_retry is still checked, and its fallback is still true. Nothing has been read about it or about tengu_mcp_first_tools_list.

Why

When a proxy blocks an MCP server, the reason is now kept with the failure, which makes it easier to see what went wrong. Claude Code also stops retrying a connection the proxy has already forbidden. The new timing data concerns slow MCP startup.

Read from
Feature flag
tengu_mcp_connect_timeout_retry Not enough to say

Nothing here resolved what this flag was doing on this version, so nothing here should be read as on or off.

This account: no value returned · anonymous baseline: no value returned · compiled default in v2.1.290: on

These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.

Read once, for one account on one subscription tier, against v2.1.290. It isn't a statement about your account. What a flag value here can and cannot tell you

How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtWhether the new report on the first tool list is sent every time or only for some sessions is not clear.

See this entry in the whole of v2.1.290 →

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