Lock Down MCP Servers with --strict-mcp-config

By default, Claude Code loads MCP servers from multiple sources: your user settings, project settings, local settings, and any --mcp-config files you pass on the command line. In automation or security-sensitive environments, that's too many moving parts.

The --strict-mcp-config flag tells Claude to only use MCP servers from the config file you specify, ignoring all other sources:

claude --strict-mcp-config --mcp-config ./approved-servers.json

Your approved-servers.json might look like this:

{
  "mcpServers": {
    "postgres": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-postgres", "postgresql://localhost/mydb"]
    }
  }
}

With --strict-mcp-config, only the PostgreSQL server from that file will be available. Any MCP servers configured in ~/.claude/settings.json or .claude/settings.json are silently ignored.

This is essential for CI/CD pipelines and shared environments where you need reproducible, predictable tool access:

# CI pipeline with exactly the servers needed for this job
claude --strict-mcp-config \
  --mcp-config ./ci-mcp-servers.json \
  -p "Run the database migration checks"

It also prevents a project's .claude/settings.json from adding unexpected MCP servers that could access resources you don't want Claude touching in an automated run.

In automation, predictability beats flexibility. Lock down your MCP servers.

via Claude Code CLI Reference