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mcp/harbor
Claude Code

once for Claude Code

io.github.stringsofthemind-oss/once

Execution-safety MCP for AI coding agents protecting consequential writes from unsafe retries.

client:Claude Code transport:stdio runtime:npm

Install once in Claude Code

run in your project directory

Held in this page only — never stored, logged, or sent anywhere but back to your screen. 

claude mcp add once -e ONCE_API_KEY=<ONCE_API_KEY> -- npx -y @once-agent/mcp

Adds it for this project only. Append --scope user to make it available everywhere. Claude Code docs

once in other clients

once MCP server