| name | pr-description-writer |
| description | Reads the current git branch diff and writes a complete GitHub pull request description: summary, changes, and testing notes. Optionally creates or updates the PR. Use when asked to write a PR description, draft a pull request, generate PR notes, fill in the PR body, or describe what a branch changes. Trigger when a user says "write a PR description", "draft my PR", "describe this branch", "what should I put in my PR", or opens a PR and wants the body filled in. |
PR Description Writer
Read the current branch diff and write a complete GitHub pull request description. Create or update the PR with one command.
Writing Style
Apply to all generated PR descriptions:
- Active voice. "Adds X" not "X has been added."
- Present tense for summary ("Adds caching layer"), past tense for context ("The old approach caused N requests per render")
- Short sentences, one idea per bullet
- No em dashes — use a comma or period instead
- No filler: "this PR", "this commit", "as per the discussion"
- Specifics beat generalities: "reduces p95 latency from 800ms to 90ms" beats "improves performance"
Step 1: Check Setup
Confirm gh is authenticated:
gh auth status
If not authenticated: gh auth login and follow the prompts.
Confirm the current directory is a git repo with an active branch:
git branch --show-current
If detached HEAD or no branch, stop and ask the user which branch they want to describe.
Step 2: Gather Diff Context
Run all three commands to build context:
File summary (what changed):
git diff main...HEAD --stat
Commit messages (why it changed):
git log main...HEAD --oneline
Full diff (how it changed):
Use origin/main first (always up to date), fall back to local main, then master:
if git rev-parse origin/main &>/dev/null 2>&1; then
BASE=origin/main
elif git rev-parse main &>/dev/null 2>&1; then
BASE=main
else
BASE=master
fi
git diff $BASE...HEAD
If the diff is very large (over 500 lines), read the --stat summary and the commit messages only. Also read the first 200 lines of the diff to understand the primary changes without processing the entire output.
Also check for an existing PR and read its current title/body:
gh pr view --json title,body,baseRefName 2>/dev/null
Step 3: Read the Format Guide
Read references/pr-format-guide.md in full before writing anything. Internalize:
- Required sections and their order
- How to write each section
- What to include vs omit
- The testing section format
Step 4: Generate the Description
Write the PR description using the format from references/pr-format-guide.md.
Rules:
- Every bullet in the Changes section must trace to something in the diff
- Do not invent testing steps that are not implied by the code changes
- If a section has no relevant content, omit it entirely (do not write "N/A" or leave it empty)
- Screenshots section: only include if there are UI changes visible in the diff
- If commit messages explain the "why", use that context in the Summary
QA checkpoint: Before presenting, verify:
Step 5: Create or Update the PR
Present the description to the user and ask: "Ready to create the PR, update the existing one, or output only?"
Create a new PR:
Pass the body via stdin to handle backticks, quotes, and newlines safely:
gh pr create --title "TITLE_HERE" --body-file - << 'EOF'
BODY_HERE
EOF
Suggest a title based on the commit messages and diff summary. The title should be imperative mood, under 72 characters: "Add Redis caching for user session lookups" not "Added caching".
Update an existing PR:
gh pr edit --body-file - << 'EOF'
BODY_HERE
EOF
Output only: Present the title and body in a code block for manual copy-paste.
After creating or updating, confirm: "PR description updated. View it at: [URL]"
