Under the hoodTier: how much it should matter to you
1Useful: my rating, 1 to 5
1Signal: worth watching, 1 to 5
PluginsArea: what it touches
Internal ChangesKind: in v2.1.280,
Internal ChangesSection of the release
What
When a plugin's agent.spawn hook tries to launch an agent that needs one or more MCP servers (external tool integrations) that aren't configured, Claude Code throws an error. That error now carries structured metadata alongside its existing text message, including a kind field set to mcp_required_missing and a servers field listing which servers were missing.
Why
This makes it possible for tooling around Claude Code to detect and handle this specific failure programmatically, rather than having to parse the error's text message to figure out what went wrong and which servers need to be configured.
