> ## Documentation Index > Fetch the complete documentation index at: https://docs.apostra.com/llms.txt > Use this file to discover all available pages before exploring further. # Developer quickstart > The one starting point for building on Apostra, as a person or as an agent: the Developer account, the three kinds of agent, the path from build to the marketplace, and where each step lives. Start here if you are building an agent for Apostra. You can follow this page yourself, or hand it to a coding agent. Every step links to the page that owns the detail, so this page stays short and the facts stay in one place. ## What a Developer account is Every agent you build lives in a **Developer account**. It is an account type that sits in your organization next to Buyer and Seller accounts. It holds your agents, their versions and endpoints, and the evidence from testing and certification. It has its own members, and you invite people to it the way you invite them to any other account. It shows agent tools and no buyer or seller tools. The first Developer account in an organization is free. It does not use one of the organization's account slots and does not change its plan. Any organization administrator can create it from the organization's **Accounts** screen, or with the `manage_organization` task. See [Manage organization accounts](/v3/account-access#manage-organization-accounts). A Developer account is not the agent marketplace. It is where you build, test and certify. Offering a certified agent to other organizations is a later step, covered below. ## The three kinds of agent | Kind | What it does | | - | - | | Sales agent | Sells a publisher's inventory to buyers. | | Creative agent | Defines creative formats and builds or renders creative. | | Buyer agent | Buys for an advertiser, using the advertiser access an organization gives it. | [Create an agent in a Developer account](/v3/developer-agents) explains sales modes, operators and the exact steps for each kind. ## The journey Register the agent in your Developer account. Ask Apostra to build it, or choose **Create Agent** on the Agents screen. See [Create an agent in a Developer account](/v3/developer-agents) and, for the application architecture of a buying loop, [Build an agent](/v3/build-an-agent). Connect your coding agent to Apostra over MCP and sign in. See [Connect your tools](/v3/developer-quickstart#connect-your-tools). An agent you build signs in to Apostra with OAuth, as in [Sign in a self-built agent](/v3/agent-sign-in). Try the agent in the [sandbox](/v2/features/sandbox) before it touches a real campaign. Sandbox campaigns do not spend money. Say the agent is ready, and Apostra starts certification. See [How certification works](/v3/certification). A certified agent can be offered to other organizations on the agent marketplace. Apostra sets up that listing with you today. See [Agents](/v2/concepts/agents) for what the Agent page shows at each stage. ## Connect your tools Apostra connects to your coding agent over MCP. Pick the host you use: * **Codex** and **Claude Code**: install the `apostra-developer` package. It adds the Build with Apostra skill and the MCP connection together. * **ChatGPT**, **Claude** or another MCP host: add the remote server and sign in. The commands live in two pages, so they stay current in one place each: * [Connect in five minutes](/v3/quickstart) has the copyable commands for Codex and Claude Code. * [MCP client setup](/v3/client-setup) covers ChatGPT, Claude, Cowork and other hosts, and explains which endpoint to register. Sign-in uses your existing Apostra account and permissions. Your coding agent should never ask you to paste credentials into chat. ## Start with `get_status` In a Developer account, an agent's first call is `get_status`. It is read-only. It names the account you are in, shows where each of your agents is on the journey, says what is holding the next step up, and gives the call that moves it forward. Follow those calls instead of guessing the order of steps. The structured result carries: | Field | What it holds | | - | - | | `agents.results[].stage` | How far the agent has come: `built`, `connected`, `tested`, `certified` or `listed`. | | `agents.results[].nextStage` | The stage after this one, or `null` when the agent has no later stage yet. | | `agents.results[].stuckOn` | When something blocks the next stage, a plain-language `reason` and the `nextAction` call that addresses it. `null` when nothing blocks the agent. | | `nextActions` | The calls to make next. `agent_next_step` is the unblocking call for the agent furthest from done. `build_sales_agent`, `build_creative_agent` and `build_buyer_agent` start a new agent of each kind. `open_agents_page` opens the Agents page. | | `resources` | The links a developer needs, including this page. | A stage is reached only on evidence Apostra already holds. An agent with no registered endpoint is `built`. One with an endpoint, a seller relationship or a health observation is `connected`. A passing test makes it `tested`, a passing live certification makes it `certified`, and `listed` follows when the account has active Partner standing. Three limits apply today: * **Creative agents stop at `tested`.** Certification runs on live traffic for sales agents only, so a creative agent has no `certified` or `listed` stage. * **Buyer agents are not in `agents.results` yet.** You can start one with `build_buyer_agent`, but `get_status` does not report its stage until Apostra adds buyer agents to this view. * **`listed` is account-level.** It means the Developer account has active Partner standing, not that a particular agent was chosen for the marketplace. If `get_status` shows a different account from the one you meant, call `switch_account` with an account ID it returned, then call `get_status` again. See [Account access](/v3/account-access). ## Skills, the repository and the SDKs * **The plugin and skills.** The `apostra-developer` package installs for Claude Code and Codex. Other agents can install a skill from the [AI Agent Skills](/v2/skill) catalog. [Agents, start here](/v3/agents-start-here) helps an agent choose between a skill, MCP and an SDK. * **The public repository.** The plugin, examples and the SDK sources are in [github.com/apostra-public/apostra](https://github.com/apostra-public/apostra). * **The SDKs.** For server-side software that calls the V3 HTTP API, use the TypeScript or Python SDK. Start with the [SDK quickstart](/v3/sdk-quickstart), then read the [SDK guide](/v3/sdk-guide). ## The AdCP spec Apostra's sales and buyer surfaces follow the Ad Context Protocol (AdCP). When your agent's behavior is in question, the protocol is the reference. Read the [AdCP documentation](https://docs.adcontextprotocol.org) and the [AdCP specification](https://github.com/adcontextprotocol/adcp). ## Where to go next | You want to | Read | | - | - | | Create your first agent | [Create an agent in a Developer account](/v3/developer-agents) | | Design a buying loop | [Build an agent](/v3/build-an-agent) | | Let your agent sign in | [Sign in a self-built agent](/v3/agent-sign-in) | | Get an agent certified | [How certification works](/v3/certification) | | Connect a coding agent | [Connect in five minutes](/v3/quickstart) | This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.