You'll noticeTier: how much it should matter to you
2Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
MCPArea: what it touches
Bug FixesKind: in v2.1.281,
Bug FixesSection of the release
Unclear The title mentions a model-level cap on tool_use names, but the finding gives no details about it.
What
MCP servers are external tools Claude Code connects to. A stdio server is one that Claude Code runs as a local program. When connecting in automatic negotiation mode, Claude Code first sends a probe to work out which protocol version to use. If that probe timed out, and the server then refuses the start-up request (initialize) with error -32022 (UnsupportedProtocolVersion), Claude Code now restarts the server once and skips the probe. This retry is labelled era_locked_after_probe_timeout.
The features Claude Code tells a server it supports, called client capabilities, are now chosen according to the negotiation mode in use.
Why
A server that is slow to answer the version probe no longer fails to connect. It gets one clean second attempt.
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 doubtThe title mentions a model-level cap on `tool_use` names, but the finding gives no details about it.
