The Value of Effective Pull Request Description
This mixed-methods study of 80,000 GitHub pull requests and 64 developers reveals that while PR descriptions are generally valued, specific elements like stating the desired feedback type significantly predict positive review outcomes, whereas explaining the purpose and code changes aids in preserving rationale and history.
Original paper licensed under CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/). This is an AI-generated explanation of the paper below. It is not written or endorsed by the authors. For technical accuracy, refer to the original paper. Read full disclaimer
Imagine you are a chef who just invented a new, delicious recipe. You want to share it with a team of other chefs so they can add it to the restaurant's official menu. But before they let you, they have to taste-test it and make sure it's safe and tasty.
In the world of software, this is called a Pull Request (PR). A developer (the chef) submits code changes (the recipe) to a team (the reviewers) for approval.
Now, imagine you hand your recipe to the head chef with no note at all. Just a stack of ingredients and instructions. The head chef has to guess: Why did you change the salt? Is this for a spicy dish or a dessert? Did you test it?
This is exactly what this research paper investigates. The authors wanted to know: Does writing a good "note" (a PR description) actually help the code get approved faster and better?
Here is the breakdown of their findings, using simple analogies:
1. The "Recipe Card" Problem
The researchers looked at 80,000 of these "recipe submissions" (Pull Requests) on GitHub. They found that many developers leave the note blank. It's like sending a package with no address label.
They also looked at "best practice guides" written by experts (like Google or Atlassian). These guides say: "You must explain what you changed, why you changed it, and how you tested it."
The team created a checklist of 8 essential ingredients for a good note:
- The Goal: What does this change do?
- The Reason: Why was it necessary?
- The Code Details: How did you do it?
- The Link: Is this fixing a known bug?
- The Feedback Request: What kind of help do you need? (e.g., "Check my math" vs. "Check my spelling")
- The Order: Which file should I read first?
- The Test: How did you prove it works?
- Screenshots: (For visual changes only).
2. The Big Surprise: What Actually Works?
The researchers ran the numbers to see if having these "ingredients" in the note actually made the code get approved (merged) faster or with fewer arguments.
The Result was mixed:
- The "Boring" Stuff Matters: If you explain what the code does and why you did it, your code is more likely to be accepted. It's like telling the chef, "I added more garlic because the soup was too bland." It makes sense, so they approve it.
- The "Magic" Ingredient: The most powerful thing you can do isn't explaining the code; it's asking for specific feedback.
- Analogy: Imagine if you told the head chef, "Please check the seasoning, but ignore the garnish."
- The study found that when developers explicitly asked for a specific type of feedback, the code was 64–72% more likely to be merged. It also made the reviewers engage more deeply. It's like giving the reviewer a map instead of a blindfold.
3. The Human Element: What Do Developers Think?
The team also surveyed 64 real developers to ask, "How important is this note to you?"
- The Verdict: Developers said, "It's super important!"
- Why?
- Understanding: It stops confusion.
- History: It acts as a time machine. If you come back to this code in two years, the note tells you why you made that weird decision.
- Efficiency: It saves time.
However, the survey also showed that developers don't think every note needs every ingredient. Sometimes a simple "Fixed a bug" is enough. But for big, complex changes, a full "recipe card" is essential.
4. When Do People Write Notes?
The study found that people don't write notes randomly. They write them when the situation demands it:
- Mature Projects: In old, established projects, people write better notes. It's like a veteran chef who knows the importance of documentation.
- Complex Changes: If the change is huge or complicated, developers naturally write more. It's a "cognitive compensation"—when the task is hard, they talk more to make sure everyone understands.
- The "Expert" Trap: Interestingly, very experienced developers sometimes write fewer notes. They assume everyone already knows what they are doing. This can backfire if the team changes.
The Takeaway
This paper teaches us that writing a Pull Request description isn't just a boring formality to check off a list. It's a communication tool.
- Don't just dump code: Explain the "Why" and the "What."
- Be a Guide: Tell the reviewers exactly what you need from them (e.g., "Please check the security, not the style").
- Context is King: The more complex the change, the more you need to talk.
In short: If you want your code to get approved quickly and happily, don't just send the "ingredients." Send a note that tells the story of the dish and tells the chef exactly what to taste.
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