Wiring sbx MCP servers

sbx mcp registers a server once on the host; the sandbox gateway is what the agent inside actually talks to. This is not the same move as adding an MCP server to Claude Code's own config — that configures the agent's client directly, per session, with no host-side credential store and no policy layer. Registering with sbx mcp buys you reuse across sandboxes, OAuth tokens that survive the sandbox, live attach without a restart, and (for governed orgs) Cedar-enforced access control. Available from sbx 0.38.0, where MCP management became first-class.

Registering a server does not attach it to anything. Attachment happens at sandbox creation with --static-mcp, or at runtime with sbx mcp load.

Register a server

sbx mcp add <name> ... writes a host-side registration. Three input shapes, three execution locations: