Custom OpenAPI Tool option missing in Vertex AI Agent Builder UI (Playbook framework)

Google Cloud Build with AI Agents
1

The Primary Blocker: I cannot find the UI path to create a custom OpenAPI-based Tool for my Playbook agent. The only “Tools” menu I can find is the Cloud API Registry, which is currently restricted to MCP (Model Context Protocol). I need to connect a standard REST API on Cloud Run, but the MCP interface returns “Invalid MCP authentication” because of the protocol mismatch.

Project Architecture:

  • Agent Type: Generative AI Agent (Playbook-based).
  • Knowledge Base: Cloud Storage bucket (21 logic files).
  • Backend: Python/FastAPI on Cloud Run (listening on 8080).
  • Access: Set to allUsers (Run Invoker) for public testing.

The Issue:

  1. The global “Tools” registry only shows MCP servers.
  2. I cannot locate the “Manage > Tools” tab within the agent-specific dashboard to register a custom OpenAPI spec.
  3. I need to configure this tool with Auth: None to bridge my agent’s reasoning with my live Supabase inventory.

Question: In the consolidated 2026 console, where is the specific screen to create an OpenAPI Tool type (not MCP) so I can paste my JSON schema and finalize the connection?