Transports

Inside a local server

A local server is a child process Claude Code starts for you. They talk over the process's stdin and stdout, so nothing is exposed to the network.

Claude Codehost + clientServer processyour machineFiles or APIwhat it wraps1. spawn command + envnpx -y airtable-mcp-server2. initializeJSON-RPC on stdin3. resultJSON-RPC on stdoutLogs go to stderr: stdout is the protocol channel4. tools/call5. read files / call API6. resultSession ends: Claude Code stops the process
add itbash
# Everything after -- is the command to runclaude mcp add --transport stdio \  --env AIRTABLE_API_KEY=key \  airtable -- npx -y airtable-mcp-server
  • Runs as you, with your files and network, so only install servers you trust.
  • Credentials come from the environment you pass with --env. Claude Code also sets CLAUDE_PROJECT_DIR.
  • One process per session. Slow to start? Raise MCP_TIMEOUT (ms).

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