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Once an account is linked, you can call its actions from your product. For the full journey up to that point — API key, connector profile, account linking — see the Embed overview.
Actions are the atomic operations in StackOne: salesforce_list_contacts, gmail_send_message, google_drive_list_files, etc. Every protocol is just a different way to invoke the same underlying actions.
All protocols route through the same engine — authentication, rate limiting, data transformation, and error recovery are handled for every action. The choice comes down to your use case and how you’re building.

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Protocols

Agent SDK

Native TypeScript/Python with framework integrations (LangChain, CrewAI, OpenAI)

MCP

Open standard for AI tools. Works with Claude, Cursor, Vercel AI, n8n

A2A

Call a pre-built agent per integration — for multi-agent orchestration.

RPC/HTTP

Call an action from any backend or script — no agent or framework.

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Which protocol?

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Mixing protocols

Many production setups combine protocols — they all use the same actions and authentication, so you can mix and match:
  • RPC/HTTP for backend jobs (scheduled syncs, data pipelines)
  • Agent SDK for your product (customer-facing AI features)
  • MCP for internal tools (Cursor, Claude Desktop for your team)
  • A2A for complex workflows (multi-agent orchestration)
Exposing hundreds of actions? Use Tool Discovery so the agent searches at runtime instead of overloading its context window — it works through both MCP (search_execute mode) and the SDK (tool search).