Error / Message
MCP server connection failed
A configured MCP (Model Context Protocol) server couldn't start or connect, so its tools aren't available this session.
MCP servers are external processes Claude Code connects to for extra tools — and like any external process, they can fail to start (a missing dependency, a bad command in the config) or fail to connect (a port conflict, a crashed process).
Start by checking the server's own config entry for typos in the command or arguments, then check whether the underlying process runs correctly outside of Claude Code at all — if it doesn't start standalone, it won't start here either.
Claude Code continues working without that server's tools while it's disconnected; it's a missing capability for that session, not a blocker for everything else.
Run the MCP server's own start command directly to see its actual errorFrequently asked questions
What does "MCP server connection failed" mean in Claude Code?
A configured MCP (Model Context Protocol) server couldn't start or connect, so its tools aren't available this session.
How do I fix it?
Try: Run the MCP server's own start command directly to see its actual error
Is this something to worry about?
Claude Code continues working without that server's tools while it's disconnected; it's a missing capability for that session, not a blocker for everything else.
Is this covered in the Claude Code Toolkit?
Yes — MCP server connection failed and patterns like it are part of the full command, hook, and template pack included with a Claude Code Toolkit subscription.
Want the full command, hook, and template pack?
This is one pattern out of the full Claude Code Toolkit — subscribe for the complete set, plus everything we add going forward.
Subscribe to the toolkit — $79/mo