Support secret manager references (e.g. 1Password op://) in MCP config and preserve user-defined claude() shell functions

Summary

When configuring MCP servers that require API keys, users currently need to set environment variables before launching Claude Code. A common approach is defining a claude() wrapper function in .zshrc to inject secrets from a password manager like 1Password CLI:

claude() {
  local api_key
  api_key="$(op item get '<item-id>' --field apiKey 2>/dev/null)"
  GOOGLE_DEVELOPER_KNOWLEDGE_API_KEY="$api_key" command claude "$@"
}

However, Claude Code redefines the claude shell function on exit (via shell integration), overwriting the user's wrapper. This forces users to either:

• Rename their wrapper (losing the intuitive claude command name)
• Re-source .zshrc after every session

Feature Request (either/both would solve this)

Option A: Native secret manager support in .mcp.json

Support secret references in MCP configuration, so users don't need wrapper functions at all:

// Example: 1Password CLI reference
{
  "mcpServers": {
    "google-developer-knowledge": {
      "type": "http",
      "url": "https://developerknowledge.googleapis.com/mcp",
      "headers": {
        "X-Goog-Api-Key": "op://vault/item/field"
      }
    }
  }
}

This could support:

• 1Password CLI (op:// URIs or op item get calls)
• Shell command substitution (e.g. { "$cmd": "op item get ... --field apiKey" })
• Other secret managers (AWS Secrets Manager, Google Secret Manager, etc.)

Option B: Preserve user-defined claude() shell functions

Provide an option to prevent Claude Code's shell integration from overwriting user-defined claude() functions on exit. For example:

• A setting like "preserveShellFunction": true
• Or detecting and respecting existing user-defined claude() functions

Environment

• Claude Code version: 2.1.76
• Shell: zsh
• OS: macOS (Darwin)

Use Case

Using the Google Developer Knowledge MCP server which requires an API key passed via HTTP header. The API key is stored in 1Password for security.