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Sweep 22 Oct 2026 · 04:32Z Build v2.1.308 527 read Stable v2.1.308 Latest v2.1.308 Next v2.1.308 Feeds RSS JSON llms.txt llms-full.txt Unofficial
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Claude Code v2.1.238 ·

MCP servers can connect lazily from a cached entry

Tool calls to a remembered MCP server could dial it on demand, but the cache behind it is off.

Nothing to try yet Notable In Development
JSON All of v2.1.238
Nothing to try yetTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
MCPArea: what it touches
In DevelopmentKind: in v2.1.238,
What probably matters to youSection of the release

Lazy connect and re-auth cache clearing both require the MCP discovery cache, enabled only by setting MCP_DISCOVERY_CACHE to true.

What

A tool call to a server that exists only as a cached discovery entry can now dial it on demand rather than failing, and /mcp re-authentication clears the cached entry before reconnecting. Both depend on the MCP discovery cache, enabled only by setting MCP_DISCOVERY_CACHE to true or by a server value, and off otherwise.

Details
  • Client-state updates carry an attempt counter and are discarded, with remote connections detached and closed, when the signed-in account moved underneath them.
  • Reconnect callbacks, tool-list-changed handlers and initial-connect retries all re-check that counter before applying anything.
  • The cached client type itself only exists when the cache is on.
Evidence

mcp_call lazy connect

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

Read from
Names in the bundleMCP_DISCOVERY_CACHE/mcp
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.

Added since A small documentation edit on Channels reference touched a line naming /mcp after this was published. * **`curl` succeeds but nothing reaches Claude**: run `/mcp` in your session to check the server's status. A `failed` status usually means a dependency or import error in your server file. To see the stderr trace, restart with `claude --de… channels-reference see the edit
Confirmed since Anthropic's documentation has since written up /mcp, on Third party connectors with remote MCP. **MCP server URL**: the HTTPS address where the server accepts MCP requests, for example `https://mcp.example.com/mcp`. After you continue, Claude checks the URL and pre-fills the authentication settings it detects, marked "Detected." connectors/custom/remote-mcp see the edit
How sure we are
One source agreesOne thing we can check says the same as this entry.
Anthropic's documentation agreesAnthropic's documentation has since written up /mcp, on Third party connectors with remote MCP.

See this entry in the whole of v2.1.238 →

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