Does ChatGPT Apps support reading standard MCP resources?

ChatGPT Apps SDK
1

I’m trying to use standard MCP resources to provide shared guidance and reference knowledge for an agent.

These resources contain information that is needed by multiple tools, such as:

  • shared workflow instructions

  • common validation rules

  • reusable domain-specific guidance

Duplicating this content in every tool description would make the tool schemas unnecessarily large and repetitive.

My MCP server exposes these resources through the standard MCP resource mechanism, but in ChatGPT Apps I have not found a way for the model to discover or read them through resources/list or resources/read.

I also explicitly asked ChatGPT to read one of the resources. ChatGPT attempted to use api_tool.read_resource, but the call returned a ResourceNotReadable error.

The Apps SDK documentation discusses resources mainly in the context of UI templates and resource links, but it is unclear whether general-purpose text resources are available to the agent.

Does ChatGPT Apps currently support reading standard MCP resources for agent guidance and shared knowledge?

If not, what is the recommended way to expose shared, on-demand guidance that is used by multiple tools?

2

No, I would recommend using server instructions for this for now, but please hang tight as things will be changing as we work through merging ChatGPT and Codex.

3

I would not assume general MCP resources are model-readable in Apps until the platform exposes a clear resources/list + resources/read path for that surface. For now I’d keep the tool descriptions tiny but add an explicit tool like get_workflow_guidance(scope) that returns the shared rules by key. That keeps the schema small, makes the read auditable, and avoids duplicating the same guidance into every tool. Resource links can still be useful for UI or human inspection, but I would not make core agent behavior depend on them being discovered implicitly.