> ## Documentation Index
> Fetch the complete documentation index at: https://docs.skybridge.tech/llms.txt
> Use this file to discover all available pages before exploring further.

# Build Your App

> The four decisions that make an MCP App

Building an MCP App means answering four questions: what the model can do, what the user sees, what the model knows, and who is asking. Each page below covers one, in build order, on the same running example: a personal shopper with a product carousel and an authenticated checkout.

| Define                | Page                              | Core APIs                                                                                                                    |
| --------------------- | --------------------------------- | ---------------------------------------------------------------------------------------------------------------------------- |
| What the model can do | [Register Tools](/build/tools)    | [`registerTool`](/api-reference/register-tool)                                                                               |
| What the user sees    | [Create Views](/build/view)       | [`useToolInfo`](/api-reference/use-tool-info), [`useCallTool`](/api-reference/use-call-tool)                                 |
| What the model knows  | [Manage State](/build/state)      | [`useViewState`](/api-reference/use-view-state), [`data-llm`](/api-reference/data-llm)                                       |
| Who is asking         | [Authenticate Users](/build/auth) | [`requireBearerAuth`](/api-reference/require-bearer-auth), [`securitySchemes`](/api-reference/register-tool#securityschemes) |

<Columns cols={2}>
  <Card title="Register Tools" icon="wrench" href="/build/tools">
    Define what humans and agents can do
  </Card>

  <Card title="Create Views" icon="palette" href="/build/view">
    Craft interactive UIs rendered in conversation
  </Card>

  <Card title="Manage State" icon="database" href="/build/state">
    Decide what the model sees
  </Card>

  <Card title="Authenticate Users" icon="key" href="/build/auth">
    Know who's behind every tool call
  </Card>
</Columns>