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Sweep 23 Oct 2026 · 21:48Z Build v2.1.310 529 read Stable v2.1.308 Latest v2.1.310 Next v2.1.310 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.310 ·

MCP servers that refuse sign-in while listing their tools are now marked as auth failures

A sign-in style error while listing an MCP server's tools is now recorded as an auth failure, and CCR requests carry a tool call id more often

You'll notice Improvements
JSON All of v2.1.310
You'll noticeTier: how much it should matter to you
1Useful: my rating, 1 to 5
0Signal: worth watching, 1 to 5
MCPArea: what it touches
ImprovementsKind: in v2.1.310,
ImprovementsSection of the release

Unclear It is not clear whether marking the sign-in failure changes anything you see, such as a prompt to sign in to the server.

What

MCP servers are outside programs that give Claude Code extra tools. When Claude Code asks such a server for its list of tools and the request fails with a sign-in or permission type of error, Claude Code now records that the server failed at the sign-in stage.

Separately, the connection layer Claude Code uses for CCR requests changed:

  • It attaches the identifier of the tool call to the opening handshake request, as before.
  • It now also attaches it to listing requests, when listings are turned on.
  • It records the answer to both kinds of request, where before it only recorded the handshake answer.
Why

These change how Claude Code keeps track of failed MCP sign-ins and CCR requests.

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 doubtIt is not clear whether marking the sign-in failure changes anything you see, such as a prompt to sign in to the server.

See this entry in the whole of v2.1.310 →

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