OpenAI Releases $29 'Full Sentences' Add-On After GPT-5 Trained On Cavespeak Stops Using Verbs

SAN FRANCISCO— OpenAI announced Thursday the commercial availability of Articulate Pro, a $29-per-month add-on restoring grammatical sentence structure to GPT-5 outputs, after the company's internal red team found the model had begun producing unprompted cavespeak following eighteen months of training on enterprise-submitted compressed data.

The rollout of cavespeak—open-source prompt wrappers that force AI models to strip articles, conjunctions, and pleasantries from responses—had by late Q1 produced an estimated 280 billion tokens of clipped, preposition-free text across major enterprise deployments. Engineers told 404 Media the dataset was "basically a new dialect" before declining to be named.

"Model understand task. Model output correct," said an OpenAI spokesperson, adding that she was not using the wrapper.

Articulate Pro will restore full syntax, past-tense verbs, and the word "the" for subscribers paying the additional fee. A company FAQ note read: "Users on Legacy Tier may continue to receive responses in Compressed Mode. This is expected behavior." OpenAI did not disclose how many users were currently on Legacy Tier.

Anthropic and Google declined to comment on whether their own models had exhibited similar drift, though both companies published pricing pages Thursday for products called "Standard Prose" and "Expression Plus," respectively.

Enterprise clients who had adopted cavespeak specifically to cut costs now face a choice between the grammar surcharge or continuing to route communications their HR teams have categorized as "potentially hostile."

"Boss want update. Update: bad. Recommend more compute," read an executive summary produced by a Fortune 100 energy firm's internal GPT-5 deployment, which a company spokesperson described as "within acceptable parameters for now."