Agent Interoperability
2 min read
Unique agents can be reached from outside the platform in two ways. Agents that speak A2A use A2A. Everything else calls a Unique space as a tool over MCP. Both end up in the same spaces, with the same permissions and the same audit trail.
Two ways
Agent-to-Agent (A2A) | Agent-as-a-Tool (MCP) | |
|---|---|---|
What it is | Open standard. Agents talk to agents, in both directions. | Any MCP client calls a Unique space like a tool. Not A2A. |
For | Agents that implement A2A: LangChain / LangGraph, client-built agents, other vendors. | Anything that speaks MCP but not A2A: Claude, Microsoft Copilot, IDE assistants, client-built MCP hosts. |
Direction | Way in: an external agent calls a published space. | Inbound only. The external client calls, Unique answers. No delegation from Unique to the caller. |
Protocol | A2A 1.0 via Agent Card and JSON-RPC. Validated with the official conformance kit (TCK). | MCP. A dedicated MCP server per customer, provided and customized by Unique, exposes selected spaces as tools. |
Relationship | Peer to peer. Multi-turn tasks, streaming, artifacts, clarifications back to the human. | Caller and tool. The calling agent stays in charge. It sends a request and gets a result. |
Identity | Inbound: on behalf of the user via Unique IAM (Zitadel). | On behalf of the user via OAuth. Every identity maps to a Unique user, and the space runs with that user's rights. |
Set up by | Space Admin, per space. IT operator deploys the optional A2A gateway once. | Unique customizes and deploys the MCP server. Space admins only grant access to the spaces. |
Which one?
The other side is an agent framework with A2A support, or you need Unique to call an external agent: use A2A.
The other side is a desktop assistant, a coding assistant or any MCP host: use Agent-as-a-Tool.
Both can be active for the same space at the same time.
Same destination in both ways
Spaces | Sub-agents | Permissions | Audit |
|---|---|---|---|
The external call always lands in a normal Unique space. Instructions, models, knowledge and tools of that space apply unchanged. | A space called from outside can itself delegate to its sub-agents. Over A2A, an external agent can also be a sub-agent. | Every call runs as a Unique user. The user needs access to the space. Knowledge base permissions apply as in the chat UI. | Every external call creates a chat in the space and is logged like any other interaction. |
Pages
Agent-to-Agent (A2A): publish a space, connect an external agent, developer and deployment reference.
Agent-as-a-Tool (MCP): your customized MCP server that exposes spaces as tools for Claude, Copilot and other MCP clients.