虎hǔ头tóu蛇shé尾wěi

Literal: tiger's head, snake's tail
Figurative: To start out with great vigor and then peter out or finish sloppily; unlike 半途而废, the stress is on the gap between a strong start and a weak end.

Where does 虎头蛇尾 come from?

It does not come from an anecdote: the image is of an animal with a tiger's head, big and imposing, that tapers off into a snake's tail, thin and slippery. The set phrase is already on record in Yuan-dynasty drama, in Kang Jinzhi's play 《李逵负荆》, and from there it passed into everyday speech. It is used as a criticism of projects, works or people that start out with great fanfare and then run out of steam. What it stresses is not quitting as such, which is what 半途而废 names, but the gap between a brilliant start and an ending that fizzles.

Source (出处): 康进之《李逵负荆》

How is 虎头蛇尾 used? Two examples

这zhè个ge项xiàng目mù虎hǔ头tóu蛇shé尾wěi，启qǐ动dòng会huì开kāi得de很hěn隆lóng重zhòng，最zuì后hòu却què只zhǐ交jiāo了le份fèn敷fū衍yǎn的de报bào告gào。
The project started strong and fizzled out: the kickoff was a grand affair, and in the end all they handed in was a perfunctory report.
这zhè次cì装zhuāng修xiū虎hǔ头tóu蛇shé尾wěi，开kāi头tóu样yàng样yàng讲jiǎng究jiu，最zuì后hòu卧wò室shì随suí便biàn刷shuā了le刷shuā就jiù完wán事shì了le。
The renovation started strong and ended sloppily: at first every detail mattered, and in the end the bedroom just got a quick coat of paint.

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