We have deployed a multi-agent ADK application using Google Cloud Agent Designer.
Our Performance Analyst subagent uses a custom MCP server registered in Agent Registry.
The MCP server is hosted on Cloud Run and requires API key authentication.
We have configured:
- An enabled Agent Identity API Key Auth Provider.
- An Outbound Binding connecting the deployed Reasoning Engine to the registered MCP server.
- The MCP server as a tool in the Performance Analyst subagent.
The binding has been verified using gcloud agent-registry bindings list.
The MCP server works correctly when called directly with X-API-Key, including successful tools/list and Search Console data retrieval.
However, requests originating from the deployed Agent Designer application contain neither an X-API-Key header nor an Authorization header. Our server therefore returns HTTP 401.
The issue persists after redeploying the agent.
We also noticed that the code exported by Agent Designer does not include registration of GcpAuthProvider through CredentialManager.
Questions:
- Does Agent Designer currently support automatic API Key Auth Provider injection for custom MCP servers registered in Agent Registry?
- Is additional configuration required to activate the Outbound Binding in an Agent Designer deployment?
- Should Agent Designer automatically register
GcpAuthProvider, or is that functionality only available when deploying ADK applications programmatically? - Is there a supported workaround that preserves Agent Designer as the source of truth for the application?