THE VERDICT
● If you need speed and cost, reduced reasoning output is a straight win. Fewer tokens, fewer round trips.
● If you need to inspect what happened, check what each vendor exposes before you commit — it is no longer uniform.
● Either way: build audit trails on actions, not reasoning. Actions stay visible.
What changed
Reasoning models generally worked by producing visible intermediate steps. You could read the chain, find where it went wrong and intervene. That was a debugging affordance that quietly became an oversight mechanism.
OpenAI's safety documentation for GPT-6 Astra states the model completes substantially more work without surfacing that reasoning. Presented as efficiency, which it is. Also a shorter record, which it also is.
THE TRADE CANNOT BE SPLIT
Work done without emitting reasoning is cheaper and faster. It is also less inspectable. Those are the same property, and no vendor can give you both.
The question is which side of it your use case sits on, and most people have never had to ask because it used to come as standard.
What to check per vendor
| Question to ask |
Why it matters |
| Are reasoning traces returned in the API response? | Visible in a chat UI is not the same as retrievable programmatically |
| Are they complete or summarised? | A summary of reasoning is a different artefact from the reasoning |
| Do they persist, or only stream? | If you cannot store them, you cannot audit later |
| Does reasoning effort change what you see? | Lower effort may mean less exposed as well as less performed |
| Are tool calls logged separately? | This is the fallback, and it is the one that holds |
Test these rather than reading documentation. Run one task on each and look at what actually comes back — vendor docs describe intent, and the response object describes reality.
What to do instead
- Log actions. Tool calls, file writes, requests and results remain fully visible on every vendor. Build the audit trail there.
- Ask for justification explicitly. Requesting a written rationale is not the internal chain, but it is checkable and costs a few tokens.
- Use known-answer tests. Less visibility makes silent errors harder to spot by inspection, so catch them by result instead.
- Do not expect this to reverse. The efficiency gain is real and commercially valuable across every vendor.
FAQ
Which model shows the most reasoning?
It varies by vendor and by reasoning-effort setting, and it is changing. Test rather than assume — run the same task on each and inspect the response object.
Does less visible reasoning mean worse answers?
No. Capability is unaffected. What changes is how much of the process you can inspect.
What should I use for compliance work?
Whatever you use, build the audit trail on actions rather than reasoning traces. Actions are logged consistently; reasoning exposure is not.