Agent Extensions

Agent Extensions

Extend agents with MCP servers, plugins, and skills — all managed per-agent from Mission Control. Extensions are applied automatically when containers start.

Extensions require nix_enabled: true on the agent. Dependencies are auto-installed via nix.

Extension Types

• MCP Servers — Connect agents to external tools via the Model Context Protocol
• Plugins — Claude Code marketplace plugins
• Skills — Custom instructions loaded into the agent's system prompt

How It Works

Saving extensions in Mission Control stops the running agent container. On the next message:

1. The gateway loads extensions from the DB, resolves any secret: references from the vault
2. The resolved extensions are passed to the container as the AGENT_EXTENSIONS env var
3. The agent-runner auto-installs missing nix dependencies for stdio MCP server commands
4. MCP servers are merged into the SDK query() call; skills are written to disk; plugins are installed/enabled