What
MCP servers are separate programs that give Claude Code extra tools. Claude Code could already hold the first turn while waiting for some servers. Two new environment variables (settings passed to Claude Code when it starts) let a host name the exact servers to wait for.
CLAUDE_CODE_MCP_PREWAIT_SERVERSnames the servers to wait for.CLAUDE_CODE_MCP_PREWAIT_SERVERS_MSsets how long to wait, in milliseconds.- They sit next to the existing
CLAUDE_CODE_MCP_CONNECTOR_PREWAIT_MSand are read only in remote worker sessions, meaning sessions started with an SDK URL. - If a named server has no matching
--mcp-configentry at startup, Claude Code logs a warning and does not wait for it. - A log message about probing servers was reworded from one about claude.ai connectors to a general
[mcp]message, so the probing seems to cover servers in general.
Why
A host running Claude Code remotely can make sure particular tools are ready before Claude starts working, instead of relying only on the general startup wait. Check that each name matches an --mcp-config entry, or the wait is skipped for it.
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It was not confirmed how the named wait is applied afterwards, or whether these variables are allowed through to the Claude Code process in…