Write the measurement you will need before the part arrives
Two months ago, working out what to buy for a roof rack, I wrote a warning into the parts list on the card for the crossbars. It said that bars in the original style usually have an aerodynamic profile with no channel on top, and that if they arrived like that the light bar would need U brackets rather than sliding bolts. It ended with an instruction to my future self: when they arrive, measure the profile.
They arrived on the fifth of October. Exactly as warned.
This is a small thing and it contains the whole division of labour, so it is worth laying out.
What the measurement showed
The channel has a twelve millimetre slot and twenty three millimetres of space inside. The bracket's foot has an oval recess sized for a hex head, and that head is a little over thirteen millimetres across.
Thirteen millimetres rotating inside twenty three does not tighten. It turns, forever. You discover that with a spanner in your hand, not through any amount of reading.
I wrote down one more thing: the depth of the channel, which decides between two nut sizes, is still unmeasured. Labelled as unmeasured rather than assumed, because an assumed dimension in a document is worse than a blank one. A blank sends you to go and look. An assumption gets carried forward, summed, and ordered against.
What the machine was genuinely good at
Within minutes I had five candidate fittings across five shops, each with price and stock, plus a no purchase workaround to try first.
Five more were eliminated with reasons worth more than the shortlist, because they are what you normally discover after ordering: one shop has no working add to cart button and will not serve a secure connection; one part costs two lei with eighty lei of shipping; one has a foot of the wrong dimensions; one is a perfect fit and ships only to the other side of the world; one has been withdrawn from the range.
That is ten suppliers read properly in the time it takes me to open three tabs and lose interest. It is the single highest value thing I use this for outside of code, and it is not clever, it is just thorough at a speed I cannot match.
The pattern, stated generally
Three parts, and only one of them is mine to do.
Predict in writing, at the moment of thinking. Not the prediction itself, the timing. The note cost two minutes in August when the thinking was fresh and was still there in October when the thinking had gone.
Name the measurement, and label it as pending. The note did not say "this might not fit". It said what to measure and why it decides. That is the difference between a worry and an instruction.
Let the search be free. Ten shops, prices, stock, shipping restrictions, eliminations with reasons. Legwork is now close to free and should be used without restraint.
The part nobody can do for me is standing in a cold garage with a tape measure, and deciding which compromise to accept.
Why write any of it down
Without the August note, the bars arrive, they do not fit, and I spend an evening annoyed and improvising.
The note solved nothing by itself. It turned a surprise into an expected event with a prepared next step, and that is the entire value of a specification in a form small enough to see all at once.
The card now says the bar is mounted. It cost about twenty lei.