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

# Choose your surface

> Four ways to call the same Brickken backend — and which one fits what you are building.

The REST API, the CLI, the MCP server, and the Skill all talk to the same backend at `api.brickken.com`. They differ in who is driving and which credential they carry.

## Start from what you already have

| You have                             | Use                        | Because                                                    |
| ------------------------------------ | -------------------------- | ---------------------------------------------------------- |
| An API key and a Brickken account    | **REST API** or **MCP**    | These are the only two clients that reach the Dapp API     |
| A funded wallet and no API key       | **Agentic API** or **CLI** | Pay per call with x402; no account needed                  |
| An MCP-capable AI agent              | **MCP**                    | One hosted endpoint, 57 tools, credentials set per session |
| A terminal and an agentic workflow   | **CLI**                    | `npm i -g brickken-cli`, then one command per operation    |
| An AI coding agent, any of the above | **Skill**                  | Teaches the agent when to use which surface                |

## The four surfaces

<CardGroup cols={2}>
  <Card title="REST API" icon="code" href="/api-reference/introduction">
    Plain HTTP. Everything the platform can do. API key for the Dapp API, x402 or API key for agentic methods.
  </Card>

  <Card title="MCP server" icon="plug" href="/mcp/introduction">
    Hosted at `https://mcp.brickken.com/mcp`. The only client that reaches the **full Dapp API with just an API key**.
  </Card>

  <Card title="CLI" icon="terminal" href="/cli/introduction">
    `brickken-cli` on npm. Agentic and RAMS workflows from your terminal. Does not reach the Dapp API.
  </Card>

  <Card title="Skill" icon="sparkles" href="/skill/introduction">
    Brickken knowledge for AI coding agents, with or without the CLI installed.
  </Card>
</CardGroup>

## What each surface can reach

|                                         |    REST   |         MCP        |       CLI       |       Skill      |
| --------------------------------------- | :-------: | :----------------: | :-------------: | :--------------: |
| Dapp API writes                         |    Yes    |         Yes        |      **No**     | Guides the agent |
| Dapp API reads                          |    Yes    |         Yes        |      **No**     | Guides the agent |
| Agentic writes (ERC-8004, agent tokens) |    Yes    |         Yes        |       Yes       | Guides the agent |
| RAMS writes                             |    Yes    |         Yes        |       Yes       | Guides the agent |
| RAMS reads                              |    Yes    |         Yes        |       Yes       | Guides the agent |
| Accepts an API key                      |    Yes    |         Yes        | RAMS reads only |         —        |
| Pays with x402                          |    Yes    |         Yes        |       Yes       |         —        |
| Where it runs                           | Your code | Hosted by Brickken |   Your machine  |    Your agent    |

<Warning>
  **The CLI cannot call the legacy Dapp API.** Two independent reasons: it has no commands or method mappers for the Dapp methods, and it attaches `x-api-key` only to RAMS reads and typed-data fetches. `brickken tx prepare --method newTokenization` forwards the method name, but the backend answers `API key is required for this method`.

  For Dapp API work, use **MCP** if an agent is driving, or plain **HTTP** if your own code is.
</Warning>

## Same backend, same rules

Whichever surface you pick, the mechanics are identical: writes are **prepared** into unsigned transactions, **signed**, then **sent**; preparing an agentic operation is free and only the send costs anything; and your private key never leaves your machine.

The surface changes the ergonomics, not the semantics — you can prepare with the CLI and send with curl.

<CardGroup cols={2}>
  <Card title="Authentication" icon="key" href="/get-started/authentication">
    The credential matrix in full.
  </Card>

  <Card title="Quickstart" icon="rocket" href="/get-started/quickstart">
    A first call on each of the four surfaces.
  </Card>
</CardGroup>