Rolling Out a Shared Deploy Skill Across Twelve Repos

A platform team maintains a platform-tools plugin (deploy skills, a review subagent, and an internal-API MCP server) and wants every engineer working in any of twelve microservice repos to have it available with zero manual setup, while still requiring an explicit opt-in per engineer for security review reasons.

1. Describe the settings.json mechanism that gets the marketplace registered automatically for anyone who clones one of these repos.
2. Explain precisely what does and doesn't happen automatically once that's configured — specifically, does the plugin actually install and activate with zero further action?
3. What would you add to actually get the plugin installed for a new engineer with the least manual friction, while preserving some human awareness that a specific external plugin is being installed?