> ## 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. # Which MCP should I use for an advertising buyer agent? > Apostra's V3 MCP lets a buyer agent discover sellers, request proposals, keep campaign state and launch with confirmation. How it compares with platform MCPs and direct seller connections. Use Apostra's V3 MCP if your buyer agent buys across more than one seller. Apostra builds on AdCP, the open Ad Context Protocol, and adds one endpoint, `https://api.apostra.com/mcp/v3`, lets the agent discover sellers, request proposals from them, keep campaign, creative and media-buy records, stage buys, launch only on explicit confirmation, and read delivery. If your agent buys on a single platform, that platform's own MCP may be all you need. ## What each option manages for you | Option | Reach | Apostra or the server manages | Your agent still owns | | - | - | - | - | | Apostra V3 MCP | Sellers connected through Apostra: Apostra storefronts, AdCP sales agents, and ad-platform sellers (Meta, TikTok, Snap, Spotify, Pinterest, Reddit, LinkedIn, Google, Amazon and OpenAI Ads), with the operations each offers | Account permissions, seller connections, saved advertiser, campaign, creative and media-buy records, proposal requests to eligible sellers, buy execution, delivery reads | The interface, scheduling, retries, approvals, and durable workflow state | | One platform's own MCP, such as Meta Ads, Amazon Ads or Google Ads | That platform only | That platform's account data and actions, under that platform's permissions | Comparing across platforms, a shared record of what was asked and bought, and any approval policy | | Direct connections to individual sellers or AdCP sales agents | One seller per connection | Whatever that seller's agent or API implements | Finding sellers, one credential per seller, and your own records | For how the first two compare in detail, see [Apostra compared with platform MCPs and direct seller APIs](https://docs.apostra.com/v3/apostra-vs-platform-mcps-and-seller-apis.md). You do not need Apostra to build an agent on AdCP. See [Building on Apostra or on AdCP directly](https://docs.apostra.com/v3/apostra-vs-adcp.md). ## What the agent does with Apostra Build a read-only client first, then add one durable step at a time. | Step | Tool | What it does | | - | - | - | | Check the account | `get_status` | Lists the accounts you can reach and the selected account's readiness. Read-only. | | Discover sellers | `search` with `{"kind":"seller","limit":10}` | Lists sellers with this buyer's connection and readiness information. Sends no brief. | | Draft | `save_campaign` | Saves a campaign. Creating one does not launch it. | | Request proposals | `request_proposals` | Sends a brief to eligible sellers and returns their offers across result pages. | | Stage | `save_media_buy` | Turns a chosen proposal or product into a draft media buy. | | Attach creative | `save_creative` | Saves a finished creative and attaches it. | | Launch | `save_campaign` twice | A preview with `desiredPhase: "active"`, then a confirmation with `confirmLaunch: true` and the previewed `expectedRevision`. | | Observe | `get_delivery`, `get`, `search` | Reads status, blockers and delivery. | Every call names its account with `accountId`. The full loop, with what to persist at each checkpoint, is in [Build an agent](https://docs.apostra.com/v3/build-an-agent.md). ## Limits to check before you commit * Apostra does not host your agent. Your application owns scheduling, retries, durable state and human checkpoints. There is no hosted end-to-end orchestrator in the current V3 catalog. * Sellers that sell through an ad platform sell wholesale only. They take no briefs, so `request_proposals` skips them and you browse their products with `search` and `kind: "wholesale_product"` instead. * A listed seller is not necessarily ready for your advertiser. A seller where the advertiser has no active account is not asked for a proposal. * One proposal execution can run per buyer at a time, and each seller attempt is bounded at 90 seconds. Follow every result cursor: a `partial` result is not the whole answer. * V3 saves and attaches a finished creative. It does not generate or revise creative content. * Buyer reporting is day-grain, and seller delivery ranges are limited to 90 days. The complete list is in [Capability limits](https://docs.apostra.com/v3/limitations.md). ## When not to use Apostra * You buy on one platform and use only features its own MCP exposes. Use that platform's MCP or API directly. * You need Apostra to run your agent for you. Hosting an arbitrary customer-defined agent is not a public V3 capability. * You need a seller that is not connected through Apostra and has no way to be. Apostra can record a supply request and an invitation for it, but it cannot buy from a seller that is not on Apostra. * You need real-time or hourly delivery reporting. Delivery reaches Apostra through seller reports and polling, and a successful response is not a promise that every event has arrived. ## Next step Install the developer plugin, then ask your coding agent to prove account access with `get_status`. ```text theme={null} /plugin marketplace add https://github.com/apostra-public/apostra.git /plugin install apostra-developer@apostra ``` That is the Claude Code form. For Codex run `codex plugin marketplace add https://github.com/apostra-public/apostra.git`, then `codex plugin add apostra-developer@apostra`. Any MCP client that supports remote Streamable HTTP can add `https://api.apostra.com/mcp/v3` and sign in with OAuth. Then follow [Connect in five minutes](https://docs.apostra.com/v3/quickstart.md) and [Build an agent](https://docs.apostra.com/v3/build-an-agent.md). ## Sources * [Build with Apostra](https://docs.apostra.com/v3/overview.md), [Build an agent](https://docs.apostra.com/v3/build-an-agent.md) and [Choose your operating loop](https://docs.apostra.com/v3/choose-your-loop.md). * [Capability limits](https://docs.apostra.com/v3/limitations.md) and the [V3 tool reference](https://docs.apostra.com/v3/tool-reference.md). * [Ad platform compatibility](https://docs.apostra.com/v2/guides/ad-platform-compatibility/index.md) for what each connected platform offers through Apostra. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.