Extensions and Integrations
Captain Who can be extended through model Providers, Skills, and MCP Servers. These three approaches address different needs:
| Approach | Best suited for | Runs external programs |
|---|---|---|
| Model Provider | Connecting a compatible language model API | No; the application sends network requests to the model endpoint |
| Skill | Teaching the Agent how to perform a class of tasks | The Skill itself does not; its scripts may require separate approval |
| MCP Server | Adding external Tools for the Agent | Yes; local stdio processes are currently supported |
Start with the built-in capabilities. Add an extension only when a task requires a specific workflow, a private tool, or another model endpoint.
Start here
- Integration overview: Choose between a Skill, MCP, and a model Provider.
- Develop a Skill: Write a reusable Agent instruction package for a project.
- Connect an MCP Server: Connect a local stdio MCP Server.
- Connect a model Provider: Configure a model API and compatibility mode.
- Compatibility: Review the currently supported scope and explicitly unsupported capabilities.
Security reminder
Third-party Skills, MCP Servers, and model services are not controlled by Captain Who. Verify their source before installing or connecting them. Do not put Tokens, Cookies, or passwords in Skill files, MCP launch arguments, issue screenshots, or public logs. An extension's name and description also do not replace permissions and approvals.