Chatgpt not using connected local APP SDK

ChatGPT Apps SDK
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1

I created an APP SDK which was working fine few weeks back but today when I tested it was not working. Chatgpt is connecting to my MCP server perfectly as my terminal logs show. My mcp server is also working fine on playground and on MCP inspector.
But when I choose my tool from connectors and then give a prompt related to the availble tools, it says looking for available tools but then doesn’t call the tool.

And when I explicitly mention the tool name to be used, it says no such tool found in the environment.

I also tried with openAi’s pizza server also, it was not calling that also

Anyone else facing this issue ? Chatgpt not calling local APP SSK

1 Like
Apps / Custom Connectors not working inside projects
4

Yes, I noticed the same thing. I had a connector to an MCP server that I created and hosted. It worked yesterday (Dec. 15) and ChatGPT was able to find the tool and use the MCP server. But today (Dec. 16) it stopped working! Like you, however, I can see that the connection to the MCP server is working and everything.

I think it must be something on the ChatGPT side. Maybe related to the new vision model they just deployed?

5

看上去你遇到的是 tool route 失效后 fallback 模式未触发 的情况，特别是在 GPT-4.5/5.1 接入新版 APP SDK 后。

:white_check_mark: 核心判断逻辑：你的 tool schema 是可发现的，但 tool activation 丢失。多数情况下是：

  • .well-known/ai-plugin.json 中 auth 字段与 manifest 中注册不一致（比如明明是 “none”，但服务端 handshake 返回了 OAuth redirect）

  • openapi.json 中 operationId 和函数名不一致（注意：OpenAI 接入不是按路径匹配，是 operationId 必须精准指令映射）

  • 新版 GPT 可能会忽略工具返回空响应（空 string / null / undefined 都可能被 silent drop）

:white_check_mark: 临时排查策略：

  • MCP Inspector 打开 verbose logging，看有没有调用意图，但被结构丢弃

  • 替换返回内容结构（哪怕先 return 一句固定字符串，也能触发一次 tool call trace）

:brain: 如果你确认 GPT 已连接但无法 call tools，很可能是 OpenAI 在 recent connector 变更中加入了 fallback 限制。

:locked: 我这边的解决方案是：为 tool 增加 echo_response 字段强制触发输出，必要时用 “x-tool-debug”: true 等 header 让系统显式路由。

6

I am not having that issue. Been testing everyday and still working today.

7

Hey Gagandeep_Singh, I got my app working again. It took a while to figure it out, but all I had to do was change the names of the tools. They have to be short and direct.

Before: start_account_research, check_research_status, get_research_results
After: research, status, results

I still don’t know why it worked for days before, and then all of a sudden quit working? :person_shrugging:

8

I dont know how and why, But if I am prompting in a chat which is inside a Project in this case my chatgpt was not calling my local tool. But on a chat window which is not inside an Project, in this case it was calling my tool properly.

1 Like
9

I have similar issues. Over the last weekend, my connector stopped working.

In the settings, all is fine, the connector is listed with all its tools. The server is running fine, which I verified.
But ChatGPT has no knowledge of this connector or its tool, even if explicitely picked from the “… More” field and if asked to list all its connectors.

A colleague added the same connector in his account and it works for him though(?). Not sure how that is possible.

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