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Sweep 10 Nov 2026 · 02:18Z Build v2.1.322 539 read Stable v2.1.311 Latest v2.1.322 Next v2.1.322 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.321 ·

MCP servers added through the SDK must now pass a check before connecting

MCP servers added on the fly through the SDK are checked before and after connecting; a refused one is closed and adds no tools

You'll notice Improvements
JSON All of v2.1.321
You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
MCPArea: what it touches
ImprovementsKind: in v2.1.321,
ImprovementsSection of the release

Unclear What the check compares a server against, such as an organization policy or an allowlist, is not known.

What

An MCP server is an outside program that gives Claude Code extra tools. Programs built on Claude Code's SDK can add such servers while running. These servers used to connect straight away. They are now checked before connecting, after connecting and while their tools are being listed.

If a server is refused, Claude Code closes it, reports it, and adds none of its tools.

Why

Rules about which servers are allowed now also cover servers added through the SDK, not only those set up in the usual way.

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 doubtWhat the check compares a server against, such as an organization policy or an allowlist, is not known.

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