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Sweep 01 Oct 2026 · 17:27Z Build v2.1.287 508 read Stable v2.1.285 Latest v2.1.287 Next v2.1.287 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.286 ·

MCP server connections gain dial-in options, and blocked-server refusal honors a new setting

The MCP connect path accepts dialInConnect and onDialStart, changing when --mcp-config servers connect; headless startup waits are now recorded

Group of 2 Under the hood Internal Changes
JSON All of v2.1.286
Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
2Signal: worth watching, 1 to 5
MCPArea: what it touches
Internal ChangesKind: in v2.1.286,
Internal ChangesSection of the release

What

MCP servers are separate programs that give Claude Code extra tools. Servers you load with --mcp-config go through a connect step, and that step has changed.

  • dialInConnect and onDialStart are two new options (callbacks, meaning functions the caller supplies) that the MCP connect function now accepts and passes on to the connection code.
  • When dialInConnect is set, the connect step skips the branch it normally takes for servers that are not marked as required.
  • The check that refuses blocked servers now also honors refusesBlockedServers.
  • Claude Code now records when a headless run (one with no interactive screen, such as -p mode) waits for named MCP servers at launch, and when the end of a turn is held back by a classifier.

Why

This changes when --mcp-config servers connect, especially servers that are not required before the first turn. If you rely on a server being connected at a particular moment in a scripted or headless run, check that it still behaves as you expect.

Read from
Names in the bundle--mcp-config
Since it was published

The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.

Confirmed since Anthropic's documentation has since written up --mcp-config, on Run Claude Code programmatically. * **MCP servers**: only servers supplied on the command line connect, for example with `--mcp-config`. In an interactive session, Claude Code also skips the automatic IDE connection unless you pass `--ide`. headless see the edit
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 what sets these options or how the timing changes in practice.
Anthropic's documentation agreesAnthropic's documentation has since written up --mcp-config, on Run Claude Code programmatically.

See this entry in the whole of v2.1.286 →

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