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Sweep 25 Sep 2026 · 19:33Z Build v2.1.283 504 read Stable v2.1.274 Latest v2.1.283 Next v2.1.283 Feeds RSS JSON llms.txt llms-full.txt Unofficial
HomeDocsClaude Code CLI 25 Sep 2026
One change · claude-code

Connect to external tools with MCP changedagent-sdk/mcp

Nearest release: v2.1.283, published 4 hours before upstream edited the page. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.

Upstream edited this page at 25 Sep 2026 23:45 UTC, give or take a minute or two: the time comes from Anthropic’s own sitemap rather than from a commit. This site recorded the change at 26 Sep 2026 00:07 UTC.

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145145Claude Code registers the servers you pass in `options.mcpServers` at startup and emits the [init message](#error-handling) once the first-turn wait, if any, resolves. Whether each `options.mcpServers` server delays the first turn, and when it connects, depends on its type:
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147| Server type | Delays the first turn? | First-turn wait timeout |
148| :------------------------------------------------------------------------------------- | :----------------------------------------------------- | :------------------------------------------------------------------------------------------ |
149| 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 |
150| 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) | Yes, until it connects and lists its tools | None; the connect and tool listing requests each have their own timeout |
147| Server type | Delays the first turn? | First-turn wait timeout |
148| :------------------------------------------------------------------------------------- | :----------------------------------------------------- | :--------------------------------------------------------------------------------------------------------------- |
149| 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 |
150| 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) | Yes, until it connects and lists its tools | [`MCP_TIMEOUT`](/docs/en/env-vars), 30 seconds by default, per connect attempt; the connection fails at that deadline |
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153153Servers loaded from [settings files](#from-a-config-file) such as `.mcp.json` or from plugins commonly show `pending` in the init message. When `options.mcpServers` holds a stdio, HTTP, or SSE server, the first turn waits for these pending servers too, up to `MCP_TIMEOUT`. When `options.mcpServers` is empty or holds only SDK servers, the first turn waits up to 2 seconds instead:
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