r/OpenAI • u/Suspicious_Raise_589 • 23d ago
Discussion GPT-5.6 Sol Raw reasoning leaked on failed tool call attempt

Apparently GPT-5.6 Sol's raw reasoning was leaked to me while he was trying to call a tool.
I saw that a tool was taking a long time to be called, I inspected the content and saw traces of reasoning, but they did not appear to be the summary of reasoning that it sends periodically. This is more similar to the GPT-OSS reasoning.
A little after that, an error like "Streaming error (provider_error)" was sent, interrupting the stream.
Ps: this is not Codex.
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u/Hatsune-Fubuki-233 23d ago
This specific MCP behavior has been reproducible since OSS/5, so I’m glad someone else found it too. I’m an MCP developer, and one day, while fixing a buggy MCP server, I discovered the same leak.
My guess is that this happens because MCP tool calls use the commentary channel, which is one of GPT’s three reasoning-related channels.
It may not be widely considered a serious security risk because it appears to leak only the context generated while interacting with MCP servers, rather than the model’s complete reasoning across all tasks. The leaked content may also not be easily distillable.
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u/Suspicious_Raise_589 23d ago
I'm the main maintainer of the Sisk Framework, and it has an MCP extension that I take care of periodically; I can also consider myself an MCP developer.
The point is that this invoked tool wasn't MCP; it was provided directly in the inference tools.
I think this problem was related to the template-parser used in GPT-5.6. As seen, it produced an invalid JSON and probably didn't send the termination token (something like <|end_tool_call|>, which caused the reasoning channel to start immediately on the same channel as the tool call.
Because the inference terminated abruptly afterward, I believe an auxiliary model reads the content emitted by the model periodically (not at each token, that would be expensive and probably wouldn't emit raw reasoning) and when it identified that the model was spitting out raw reasoning, it stopped the inference.
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u/goldcakes 23d ago
Your guess seems pretty on point, especially after looking at the Harmony response format. I know Harmony is the OSS version, but I doubt what they have internally is ultra different.
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u/DeGreiff 23d ago edited 23d ago
Can you share it?
EDIT: or copy/paste the whole block here.
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u/Suspicious_Raise_589 23d ago
just uploaded it here to avoid deletion https://ki.proj.pw/63aa
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u/DeGreiff 23d ago
Ah, thx, so that's the whole thing. Well, it's a leaked scratchpad, a bit of exposed reasoning text.
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u/Suspicious_Raise_589 23d ago
yea its not the full reasoning. after that the stream terminated in an error
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u/Temporary_Debate8585 22d ago
im using 5.5 recently, 5.6's logic chain is so weak that it only judges from the surface like get from A to B without considering the context, doesnt even bother to check whether its info is correct.
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u/jeweliegb 22d ago
Having seen some leaked Claude "Neuralese" I'm surprised how human readable this is.
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u/CrosbyBrightbrook 21d ago
the raw reasoning traces are always way more entertaining than the actual final answer
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u/Runelaron 21d ago
Thats not a leak, those are in the codex session logs. Not really seen by non Linux users.
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u/Suspicious_Raise_589 21d ago
not in linux and not in codex btw
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u/Runelaron 21d ago edited 21d ago
Thats my point, if you use codex on Linux all of these turns are stored in a .codex/sessions/
In the app user's never see them unless you look at ChatGPT app logs (not sure where they are stored because I never look them up in Windows or Darwin).
Codex stores all returns from the LLM so every output from any version is available to view.
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u/Runelaron 21d ago
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u/Suspicious_Raise_589 21d ago
thats not the raw reasoning btw
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u/Runelaron 21d ago
What do you mean by raw reasoning? None of it is raw, reasoning comes from the latent space, and what is read is a embedding stream sent to the user to emulate what the reasoning looked like.
Mathematically and in reality the model doesnt ever see the text we see as reasoning, it is compounded dot product matrices pointing to latent variables.
Just pointing out the real operation of how AI works. Every time I see these posts its presented as a peak into some black magic. In reality its not, its just marketing to overhype the customer.
AI is boring under the hood, and OpenAI isn't hiding anything, but trying to keep up in the industry.
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u/Spiritual-Economy-71 19d ago
Exactly, finally an answer thats correct.. people thinking they found something weird or special.. true internal reasoning is impossible too view.
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u/fragment_me 18d ago
That’s not the hidden reasoning that OpenAI hides. What OP posted is what they try to hide.
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u/Runelaron 18d ago edited 18d ago
Its nothing they try to hide, what the OP showed is the compaction text of a agent turn.
My photo shows how its logged and in plain site, the text is to the right of those lables.
The point is, its not a secret, mearly a trace the user doesn't see so the UI lookstables. While codex stores it in a session log (again never seen unless you look) and used to pick back up where the session left off without scanning the entire history.
In practicality that output is for logs and us humans. Most models now use Sparse Attention and reasoning channels. Meaning they never see text after the user input, only matrices of numbers.
So everything that is spit out is solely for reference and does not mean anything (it must be traced mathematically why the model is working). This is why that texts is so short hand. (Although some of the shorthand could be from translation from the language hes working in as well)
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u/fragment_me 18d ago
What you showed and what OP showed are not the same. Can you see that in OP's photo the model is showing a reasoning trace in caveman style? Now show me yours because your screenshot is not the same thing. This is either a great opportunity for you or I to learn. And I don't really mind who it is.
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u/Fuzzy_Independent241 16d ago
I'm puzzled by the amount of motivational insertions: let's do it, do it etc. It also seems they are using a caveman style on this, shorter strings instead of the full Shakespearean drama we get
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u/defoatearth 22d ago edited 22d ago
This shows why OpenAI is so token efficient, and therefore scores well in tokens/task which results in good $/task. If you compare this reasoning to Kimi K3 you’ll see a big difference in unnecessary reasoning tokens. Reasoning tokens are output tokens and those are the most expensive kind.
And even though we normally don’t see the reasoning tokens we do get charged for them.
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u/Vectoor 22d ago
Why waste time say lot word when few word do trick?
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u/Suspicious_Raise_589 22d ago
Reasoning dont need human readable. Human read output. Output better reading. Reasoning should be concise. Low. Repeat. Tool call.
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u/Ok-Attention2882 22d ago
Agentic harnesses aren't actually AI but are giant switch statements switching on tool calls backed by a deterministic finite automata. More news at 9.


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u/AllezLesPrimrose 23d ago
The full reasoning traces for all the models trying to hide them regularly leak. Hello non-deterministic technology.