Fable
Three letters after the tea stove heat was set wrong
The letter room in Lighthouse Town had a tea stove. When the stove fire was low, the ink dried quickly and the handwriting was neat; when the stove fire was high, the ink flowed and the brushstrokes varied. The letter carriers called it the heat for replying.
Early on, all letters used the same heat. Billing reminders were steady, but holiday greetings were stiff; creative copy was a bit lively, while legal notices seemed loose. The newcomer thought the hotter the fire, the smarter. He turned up the furnace, and the replies contained many fresh expressions—along with discounts that should not have been promised and details that had not been confirmed.
Another person turned the fire down to the lowest. Errors decreased, but all answers crowded toward the most common sentence patterns, explanations of complex questions seemed rigid, and users felt the system did not understand them. The shopkeeper began adjusting the heat by task. Refund policies, compliance explanations and amount confirmations used low heat; campaign titles, internal brainstorming and synonym rewriting could be slightly higher.
They also looked at the heat setting together with the candidate pool. Adjusting only the heat without looking at top-p might still let strange words in; doing only top-k without adjusting the heat might make the answers too concentrated.
After launch, quality incidents dropped noticeably. The team no longer argued about whether the machine had personality, but asked how much randomness the current task needed and how much variation it could tolerate. The shopkeeper then divided letters into several categories. Debt collection used a low flame, holiday greetings used a medium flame, and only attracting new customers was allowed to use a high flame; next to each category were promises that must not be crossed.
Once the shop needed to write an apology letter, and the newcomer wanted to stoke the fire high to appear enthusiastic. The old manager had him read it to the accountant first, and the accountant pointed out that two sentences would be taken by the customer as a compensation commitment, so the fire was lowered by half a notch.
This small incident made everyone stop and review. They did not rush to swap in a more impressive-sounding explanation, but instead wrote down clearly, one by one, the entry points that went wrong, the rules that were misunderstood, and the boundaries that needed to be preserved.
Gradually, the letter office stopped arguing about which heat level was best, and instead first asked what this letter feared: rigidity, or loss of control; dullness, or saying too much. The tea stove still burned every day. The real lesson is that creativity and controllability both have a price, and the heat level must be tied to business risk.