Domain 2 of 3 · Chapter 12 of 15

Create a multi-agent solution by using A2A protocol

Unlock the complete study guide + 1,040 practice questions across 16 full exams.

Bundled into the existing Designing and Building Integrated AI Agent Solutions in Copilot Studio premium course — no separate purchase.

14-day money-back guarantee — no questions asked.

Included in this chapter:

  • What you are actually delegating over A2A
  • Choosing A2A over MCP, a REST tool, or Activity Protocol
  • Filling in the Agent2Agent form
  • The agent card, and the filename the docs dispute
  • The description is your routing control
  • Authentication: None, API key, or OAuth 2.0
  • Why the connection is reusable, and how far it reaches
  • What crosses the boundary on every delegated turn
  • Testing the delegation and reading the round trip
  • Taking an A2A pilot to production
  • How these choices show up in questions

Choosing among the three ways an agent reaches something external

ConsiderationA2A connectionMCP server toolREST API tool or custom connector
What is on the far sideAn agent with its own model, tools and orchestrationA server that publishes a collection of model-callable tools and resourcesOne API's operations, described by an OpenAPI specification
What crosses on a callA task, plus contextId, message IDs, locale, content parts and the full chat historyTyped inputs for one tool call, and that call's typed outputAn HTTP request and its response
Who decides how the work gets doneThe external agent, using its own reasoning; its tools are opaque to your orchestratorYour orchestrator selects which tools to invoke and synthesizes the final outputYou do, when you author the call
Multiturn supportFull, because contextId allows context management across agentsLimited, because context management stays with the orchestratorSingle request and response
How the far side is discoveredAn agent card, fetched from the well-known path under the endpoint you enteredServer-owned metadata, listed from the server itselfThe OpenAPI specification you import
Where it lands in the productThe Agents page, added with Add an agentThe Tools pageThe Tools page
Microsoft's one-line ruleDelegate tasks to another agent, not just call APIsUse MCP tools or resources with MCP serversConnect to APIs or basic HTTP services with custom connectors or HTTP tools

Decision tree

Is it one API or HTTP servicedescribed by an OpenAPI spec?yesCustom connectors or HTTP tools(the REST API tool import)noDoes somebody else publish andmaintain callable tools for you?yesMCP server tooladded on the Tools pagenoWas the agent built with theMicrosoft 365 Agents SDK?yesConnect it with theActivity ProtocolnoIs it a published Copilot Studioagent in this environment?yesConnect it as an existingCopilot Studio agentnoDoes it reason about the taskand compose its own answer?yesConnect it over the A2A protocolAgents page, then Add an agentnoNo reasoning layer to delegate to:revisit the options above
Cheat sheet

Cheat sheet

  • Use A2A for externally hosted reasoning agents
  • Delegate tasks rather than model the agent as an API
  • Use the standard A2A communication contract
  • Combine A2A with other integration models
  • Enter the A2A communication endpoint
  • Populate routing metadata from a valid agent card
  • Match A2A authentication to the external endpoint
  • Create the endpoint definition and connection
  • Use A2A metadata for multiturn continuity
  • Validate delegation from the Test canvas
  • Confirm the A2A round trip in external logs
  • Secure the public A2A endpoint for production
  • Review external A2A agents beyond endpoint authentication

Unlock with Premium — includes all practice exams and the complete study guide.

Also tested in

References

  1. Connect to an agent over the Agent2Agent (A2A) protocol
  2. Understand the Agent2Agent (A2A) protocol - Microsoft Learn training
  3. Connect a Copilot Studio agent to an A2A-enabled agent - Microsoft Learn training
  4. Add other agents overview
  5. Connect to an A2A agent endpoint from Foundry Agent Service
  6. Orchestrate agent behavior with generative AI
  7. Test and validate an A2A agent connection - Microsoft Learn training