Annealing trades a real property gain for a real shape risk
Controlled reheating of a printed part, generally below its material's deflection temperature, then slow cooling, can genuinely raise heat resistance or relieve internal stress left over from rapid layer-by-layer cooling during printing. That benefit is real, but so is the cost: the part will shrink dimensionally, and any unsupported or overhang-heavy feature is prone to sagging or warping while briefly softened. This tool weighs that tradeoff against your specific objective and constraints rather than treating annealing as a free upgrade.
How the tradeoff works
A fit-critical dimension combined with an objective other than stress relief raises real caution, since dimensional shrinkage directly threatens the fit. Supports or unsupported overhangs raise the warping risk specifically, regardless of objective. In every case, the tool recommends testing on a sacrificial piece with the same geometry first, since shrinkage and warping behavior vary enough by material and geometry that no general number substitutes for an actual test.
Worked example
Objective is increased heat resistance, the part has a fit-critical dimension, and has an unsupported overhang: the tool flags real risk given both the fit-critical dimension and the overhang, and recommends testing a sacrificial piece with the same geometry before committing, since dimensional shrinkage here would directly threaten the part's fit.
A common mistake
A frequent error is annealing a finished, load-critical part directly instead of a sacrificial test piece first, discovering the warping or shrinkage only after the real part is already compromised. Since the whole value of a test piece is catching a bad outcome before it costs you the actual part, skipping that step defeats the purpose of testing at all, even when time pressure makes it tempting.
Limitations
This compares annealing's potential thermal/strength benefit against its dimensional-change and support risk qualitatively; it does not predict the exact shrinkage or warping for your specific part and material. Always test on a sacrificial piece with the same geometry first.