# Reference

URL: /code/reference · Id: `page:code/reference`

> The API, SDK, CLI and MCP references, one page per Noun in each, generated from the registry.

Every [Verb](/business/nouns/verb) on every [Noun](/business/nouns/noun) in four [Interfaces](/business/nouns/interface), one page per Noun in each.

| Reference | What it holds | Setup and rules |
| --- | --- | --- |
| [API reference](/code/api/reference) | Routes on api.sb, with the JSON each takes and returns | [API spec](/code/api/spec) |
| [SDK reference](/code/sdk/reference) | Typed methods on `$`, the `startup-builder` client | [SDK spec](/code/sdk/spec) |
| [CLI reference](/code/cli/reference) | `startup-builder do` commands for a terminal or CI | [CLI spec](/code/cli/spec) |
| [MCP reference](/code/mcp/reference) | `do` programs for an agent on the api.sb MCP server | [MCP spec](/code/mcp/spec) |

Each per-Noun page opens with a link to the Noun page it is the code view of, and each Noun page links its four reference pages. [One Verb, four Interfaces](/code/interfaces) sets every operation side by side.