MCP Configuration
MCP server missing required environment variables
Many MCP servers need their own API key or config value passed in as an environment variable — without it, they fail to start or authenticate.
A server that wraps a third-party API usually needs its own credential for that API, separate from anything Claude Code itself uses. That value has to be set in the server's own env block in its MCP config, not assumed to be picked up from your shell automatically.
This tends to produce a confusing failure: the server process starts, but immediately fails or reports being unauthenticated, which looks like a connection problem rather than a missing credential.
Re-reading the specific server's setup documentation for which environment variables it expects is usually faster than debugging from the failure alone.
Check the MCP server's docs for which env vars it requires, and confirm they're set in its config entryFrequently asked questions
What does MCP server missing required environment variables do in Claude Code?
Many MCP servers need their own API key or config value passed in as an environment variable — without it, they fail to start or authenticate.
How do I use it?
Try: Check the MCP server's docs for which env vars it requires, and confirm they're set in its config entry
Any caveats to know about?
Re-reading the specific server's setup documentation for which environment variables it expects is usually faster than debugging from the failure alone.
Is this covered in the Claude Code Toolkit?
Yes — MCP server missing required environment variables and patterns like it are part of the full command, hook, and template pack included with a Claude Code Toolkit subscription.
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