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LangBot ships four extension mechanisms in parallel — plugins, MCP, Skills, and the sandbox — and they are easy to confuse. This page sorts out what each one does and when to use it.

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One-line Summary

  • Box execution environment: lets the Agent run commands and read/write files; isolation depends on the selected backend
  • Skills: on-demand instruction packages that hand the Agent a specialized workflow when needed
  • MCP Server: connects to external tool services
  • Plugin: a long-running extension process that can ship its own config page, event listeners, and knowledge components

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Comparison

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Pipeline Binding

Skills, MCP Servers, and plugins are all pipeline extensions. After installing or creating them in the WebUI, the pipeline extension config still decides where they’re enabled:
  • Enable all extensions, or
  • Bind only specific extensions
Skill binding decides which skills the Agent can see (it controls the <available_skills> list). The actual skill content is only injected after the Agent calls activate.

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Backends and Isolation Boundaries

The Box API, Agent tools, session scopes, lifecycle, Skills, and stdio MCP hosting work the same across backends, but their security properties differ. Docker, nsjail, and E2B provide their respective sandbox boundaries. Host uses processes on the Box Runtime host directly and is only for trusted local development. Selecting Host does not change the WebUI and does not give separate sessions host-level isolation.

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Troubleshooting Map

Sandbox built-in tools and Skills currently target the built-in Agent. External runners (Dify, n8n, Langflow, Coze, etc.) should use their own tools and execution model.