The Apps SDK works through MCP, too. We’re a go!
Do you all have “Workspace” Accounts?
It started working, then failed again with “Hmmm… something went wrong”
Debugging shows it’s trying to call an endpoint that’s unavailable to me as a Plus user:
401 (“Must use workspace account for this operation”)
lol..so you need a workspace account ? XD i have but not work at all omg
And still no comms from OpaqueAI - this is getting ridiculous.
I’m supposed to be testing this to determine if my client should spend the money here or stick with Claude (where it all works).
If I’d implemented a rollout like this my job would be on the line.
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I’m experiencing the same issue with my tools being grayed out in Settings | Connectors | Create. I see the calls to list/tools on my MCP Server and the tools are shown , but they are grayed out. I’m in developer mode and can toggle the tool but it’s unable to discover and call my tool.
I’m an Enterprise Workspace admin in developer mode experiencing the same issue as most of the posters in this thread.
how you have activate the developer mode ?
Settings - Apps and Connectors:
Scroll down and you should see Advanced Settings:
When developer mode is active, the chat prompt has an orange border with “Developer Mode” tab (Memory is Off):
@Rich_Jeffries Even I am on Plus subscription, but I do not encounter workspace error at all. ChatGPT is able to call the tools smoothly without any error. Only issue left is tools are greyed out (but internally they are enabled).
Maybe you should check the oAuth section of your code. I remember that when I had tested my MCP server in Claude AI, I did not return client_secret in my HTTP POST “/register“ section. But the same code did not worked for ChatGPT. Then I introduced client_secret property in JSON object and it started working for ChatGPT
{
client_id: clientId,
client_name: clientName,
client_secret: clientSecret,
redirect_uris: redirectUris
}
Above is JSON response where you can see client_secret. To my surprize, Claude AI ignored client_secret where-as ChatGPT required it as mandatory (I asked ChatGPT to fix my code)
i dont have the advanced settings nor developer mode in team plan (business plan) but i can create custom mcp but not work at all after creation.
@cmar say have enterprise plan i think is more similar to the team plan, for this i request to him how he put the developer mode on.
3 Likes
I’m having the exact same problem. Also not seeing the Advanced sections in settings, that’s often mentioned as the place where Developer mode should be enabled.
1 Like
Hello. I have slightly different problem. I establish successful connection to the Connector but I get an error message “Can’t be used for search”. I do have a “search(query: str)” tool that returns {“results”: list[SearchResult]} and each SearchResult contains id, title, snippet and url, as well as other domain specific fields. Does someone know what could be the issue or can reference me to another doc/thread where the spec is explained?
I have the exact same issue on my Team Business plan with the MCP server I created and tested successfully. I can connect the MCP server, but it doesn’t list any custom tools, and doesn’t see them if I try to enable connectors in the chat.
The advanced tab doesn’t show up as well.
The MCP worked with Developer Mode on a Plus account two weeks ago. The Plus no longer supports Custom MCP, so… it doesn’t work anywhere at the moment.
Tested it with Claude - the MCP works fully.
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Solar System Example has same issue with tools being grayed out. I checked out the example Apps repo (github: openai/openai-apps-sdk-examples) and ran the Solar System project, verified it’s working with mcp-inspector, added it as a connector, but all the tools are still grayed out.
Same issue i’ve have a business plan but I could not use a custom MCP any more, tools are not added and I don’t even have a developer mode.
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The Search and Fetch doesn’t need to be decorated as MCP Tools.
What search providers are you trying to use? e.g. Google and Github need api keys.
I have the following net9/C#:
public sealed class SearchInput
{[Required, JsonPropertyName(“query”)] public string Query { get; set; } = string.Empty;
[JsonPropertyName(“topK”)] public int? TopK { get; set; } = 10; // 1..50}
public sealed class SearchHit
{[JsonPropertyName(“objectId”)] public string ObjectId { get; set; } = string.Empty;
[JsonPropertyName(“title”)] public string? Title { get; set; }
[JsonPropertyName(“url”)] public string? Url { get; set; }
[JsonPropertyName(“snippet”)] public string? Snippet { get; set; }
[JsonPropertyName(“score”)] public double? Score { get; set; }}
public sealed class SearchResult
{[JsonPropertyName(“results”)] public List Results { get; set; } = new();}
public sealed class GoogleSearchOptions
{public string? ApiKey { get; set; }
public string? CseId { get; set; }}
Program.cs (DI)
builder.Services.AddHttpClient(c =>
{
c.BaseAddress = new Uri(“https://www.googleapis.com/”);
c.DefaultRequestHeaders.UserAgent.ParseAdd(“EchoConnector-DeepResearch/1.0”);
});
builder.Services.AddSingleton(new GoogleSearchOptions { ApiKey = googleKey, CseId = googleCx });
Implementation:
public async Task SearchAsync(SearchInput input, CancellationToken ct)
// Run your query and return list
//SearchAsync should present as simple “search”
I don’t know about other native OAI apps, but the Android app doesn’t surface the DevMode stuff, only on the web.
Thank you for you reply. If I don’t decorate the search and fetch, ChatGPT return a different error that the connector doesn’t meet their spec and denies the connection.
Also, I don’t use Google or any other 3rd party search engine. I’m connecting my custom MCP Connector, I want ChatGPT to access my app’s data. It doesn’t have any authentication, yet, as I want to keep it as simple as possible for now.
Comparing between my classes and yours, I see that you don’t have any additional domain specific fields. However, even removing those on my side didn’t resolve the error “Can’t be used for search”. Here is some of my code on python/fastmcp:
class SearchResult(TypedDict, total=False):
…ChatGPT-compatible fields
id: str
title: str
snippet: str
url: Optional[str]
…Domain fields
system_id: str
collection_id: str
collection_name: str
class SearchResponse(TypedDict):
results: list[SearchResult]
@mcp.tool
async def search(query: str) → SearchResponse:
… Descriptive doc string
… HTTP API calls to my app
… Parsing the results to match the SearchResponse
Note: My MCP connector works fine in Claude.
i have try to reconnect my mcp with your advice but not changed the situations, in my case still not retrieve tools.. in playground works
Hello,
I’ve been using a custom MCP connector with ChatGPT Developer Mode.
It was working correctly up until a few days ago — the connector attached successfully, ChatGPT listed all of my tools, and I could call them (for example, write_file wrote a file to my local PC through my MCP server).
Now, even though my MCP server still responds normally (OAuth handshake succeeds, initialize and tools/list both return 200 and show all tools when I query it directly), Developer Mode in ChatGPT shows “something went wrong” and no longer lists or calls any of the tools.
The issue began around October 7-8 2025 and happens even in a brand-new chat or after disconnecting/reconnecting the connector.
I’ve verified that:
The server is reachable at the same root URL as before.
/oauth/token, / (for JSON-RPC), and /tools/list all return expected responses.
Restarting Flask, re-adding the source, and clearing caches do not help.
It seems like a regression or outage in Developer Mode connectors.
Could you please confirm whether there’s an ongoing issue or a required change to the connector spec?
Thank you!