Custom REST resource not visible to new App Builder backend

💬 Queries and Resources
1

  1. My goal:
    I want to connect a custom REST API resource named openAIRest to backend functions in the new Retool App Builder so my app can call the OpenAI Files API, Vector Stores API, and Responses API with file_search.

    1. Issue (after retrying it multiple times):

      openAIRest is still not visible to the App Builder backend. /backend/resources/ only contains ai/ (anthropic/, openAIProvider/), retoolStorage/, smtp/, and sql/ — no new resource folder, and a full-tree search finds no reference to it anywhere.

    2. Steps I've taken to troubleshoot:

    • Confirmed the custom REST API resource openAIRest was created and saved.

    • Confirmed the resource uses the OpenAI base URL and a project-scoped API key.

    • Refreshed and re-opened the App Builder.

    • Re-checked /backend/resources/ multiple times.

    • Searched the full backend tree for openAIRest and similar resource definitions.

    • Confirmed only existing resources such as ai/openAIProvider, retoolStorage, smtp, and sql/retoolDb are exposed.

    • Did not create any workaround or proxy because I want to use the supported Retool approach.

    1. Additional info:

    • Retool Cloud

    • Using the new App Builder

    • Custom resource type: REST API

    • Resource name: openAIRest

    • Goal is authenticated backend access to https://api.openai.com

    • The existing Retool-managed openAIProvider is insufficient because it only exposes text generation and not Files, Vector Stores, or Responses file_search.

    Question:
    Is there a supported way to make an organization-level custom REST resource available to backend functions in the new App Builder? Is there a sync, import, permission, or connection step I am missing, or are custom REST resources currently not supported from App Builder backend functions?

2

Summary

On Retool Cloud using the new App Builder, a custom REST API resource (openAIRest, pointing at the OpenAI API) was created and saved but never becomes visible to the app's backend functions, and the question is whether there's a supported way to expose an org-level custom REST resource to the new App Builder or if a sync/permission/connection step is being missed.

AI Response

This is a known resource-discovery behavior in the new App Builder where a resource created after the app was generated isn't surfaced to the agent. The supported fix is to hard-refresh the builder and then initialize a brand-new chat thread so the agent re-scans available resources, and to explicitly @-tag the resource by name to have the agent connect it. Confirm the resource and app are in the same workspace and that the resource is shared with a group where you hold Edit or Own access, since the agent only surfaces resources you can edit or own. Retool staff also confirmed on July 31, 2026 that they shipped changes significantly improving resource discovery, so retrying after a refresh and fresh thread should now pick up the custom REST resource.

Sources

:bookmark: App won't surface an existing Google OAuth 2.0 REST resource
A near-identical case where a REST resource created via Resources > Create new wouldn't surface to a new App Builder app; Retool staff confirmed the bug, gave the refresh + new-chat-thread workaround, and confirmed a fix that significantly improved resource discovery.
:bookmark: Work with data and functions in apps | Retool Docs
The supported guide for connecting resources in new apps, confirming the agent only connects resources you have Edit or Own access to and that you can @-tag a resource by name to have it used.

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