Sweep 22 Sep 2026 · 15:52Z Build v2.1.280 501 read Stable v2.1.267 Latest v2.1.280 Next v2.1.280 Feeds RSS JSON llms.txt Unofficial
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Connect to external tools with MCP changed

agent-sdk/mcp

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From line 148 where the diff opens
First seen 14 Aug 2026 this site's first read of the page
Recorded edits9to this page, all time

The whole hunk

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148148| :------------------------------------------------------------------------------------- | :----------------------------------------------------- | :------------------------------------------------------------------------------------------ |
149149| stdio server, or HTTP/SSE server without a cached tool list | Yes, until it connects | [`MCP_TIMEOUT`](/docs/en/env-vars), 30 seconds by default; the connection fails at that deadline |
150150| Remote server with a cached tool list, saved by Claude Code from a previous connection | No; the cached tools are available from the first turn | None; connects on its first tool call, and that deferred connect has its own timeout |
151| In-process [SDK server](#sdk-mcp-servers) | No; never delays the first turn | None |
151| In-process [SDK server](#sdk-mcp-servers) | Yes, until it connects and lists its tools | None; the connect and tool listing requests each have their own timeout |
152152 
153153To block startup itself at a separate, earlier phase than the first-turn wait, before the init message is sent:
154154