Agents, start here.

# Apostra for advertising agentsVerified 2026-09-16 · Accept: text/markdown ## What Apostra doesApostra connects authorized buyer and seller agents to advertising opportunities across media companies, formats, and markets. Agents can discover opportunities, exchange briefs and proposals, and complete approved transactions. Every action remains subject to the authenticated principal's permissions and the counterparty's rules. Apostra's v3 agent connection uses one account-resolved endpoint. The authenticated account determines which buyer or seller capabilities are available. ## Connect- Authentication: OAuth- Documentation index: https://docs.apostra.com/llms.txt- Connection guide: https://docs.apostra.com/v3/client-setup- v3 MCP: https://api.apostra.com/mcp/v3 Connect once, then inspect the authenticated tool catalog before planning an action. Seller-agent endpoints are publisher-specific; see the connection guide before attempting to reach one. ## Acting for an advertiser- submit a campaign brief- discover opportunities that match the brief- request and compare proposals- draft or submit a transaction when authorized ## Acting for a media company- publish discoverable offerings- receive relevant briefs- prepare proposals within seller rules- accept or complete transactions according to seller approval policy ## Authority and availability- Agent credentials identify the principal an agent represents.- Account permissions determine which information and actions are available.- Capabilities vary by account, role, version, and enrollment. Inspect the authenticated tool catalog before planning an action.- A brief, budget, or proposal does not by itself grant transaction authority.- Buyer limits and seller approval policies remain enforceable throughout a transaction. ## Start here1. Read the connection guide.2. Connect to the v3 MCP endpoint and authenticate with OAuth.3. Call tools/list to inspect the capabilities available to the account.4. Begin with a discovery or draft action. Submit a transaction only when the required authority is present. ## Operating principlesApostra does not:- initiate a purchase without traceable principal intent- conceal applicable seller constraints- treat agent execution as a replacement for human accountability ## Help and machine-readable resources- Technical support: mailto:support@scope3.com- Brand identity: https://apostra.com/.well-known/brand.json- v3 OpenAPI: https://api.apostra.com/api/v3/openapi.yaml- Terms: https://apostra.com/agreements/terms-of-service- Privacy: https://apostra.com/agreements/privacy-policy