pr-description-skill

A writing guide for pull-request descriptions, which explain proposed code changes to reviewers, in the microsoft/apm GitHub repository.

In plain words
What is it for?
Use it to draft or fill in a pull-request body, including when opening a pull request or summarizing a branch.
Why use it?
It helps produce a complete review document that explains the problem, solution, implementation, trade-offs, diagrams, and validation evidence.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/microsoft/apm/pr-description-skill
Any agent
npx skills add microsoft/apm --skill pr-description-skill
Clone the repo
git clone --depth 1 https://github.com/microsoft/apm

Made for: Claude Code, Codex.

Per session 131 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,074 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00131 $0.04074
Opus 5 $0.00066 $0.02037
Sonnet 5 $0.00026 $0.00815
Haiku 4.5 $0.00013 $0.00407

Measured 2d ago against content hash d07254e9d0b9, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

pr-description-skill scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/run_evals.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.agents/skills/pr-description-skill/SKILL.md · 341 lines

How it starts

The opening of the file, as written. The whole thing — 341 lines — stays where its author put it; the contents beside it link to each section on GitHub.

PR Description Skill -- Anchored, Concise, Validated PR Bodies

When to use

Trigger this skill on any of the following intents:

  • "write a PR description"
  • "draft a PR body"
  • "open a PR" / "open this PR" / "let's open the PR"
  • "fill in the PR template"
  • "summarize this branch as a PR"
  • "create the PR write-up"

Reusable for any PR against microsoft/apm. The output is one markdown file that the orchestrator pastes into gh pr create --body-file or surfaces to the maintainer.

Output charset rule (read this first)

The repo-wide encoding rule at .github/instructions/encoding.instructions.md constrains source files and CLI output to printable ASCII because Windows cp1252 terminals raise UnicodeEncodeError on anything else. PR comments are NOT source code and NOT CLI output -- they are rendered by GitHub's Primer engine, which expects UTF-8 GitHub-Flavored Markdown.

Two distinct rules therefore apply:

  1. Source files in this bundle (SKILL.md, assets/*) MUST stay ASCII. They live in the repo and are subject to .github/instructions/encoding.instructions.md.
  2. The PR body output the skill produces MUST be UTF-8 GitHub-Flavored Markdown. Use em dashes, smart punctuation, alerts, collapsibles, task lists, and Unicode where it improves readability. Mermaid diagram labels MAY use Unicode -- there is no constraint here. The output is consumed by GitHub's renderer, not by a Windows terminal.

A previous version of this skill incorrectly required ASCII in the PR body. That made the output unreadable: no alerts, no collapsibles for long evidence, no em dashes, no smart quotes. Reviewers had to scroll through hundreds of flat lines instead of scanning a body shaped by GFM features.

Concision targets (hard ceilings)

The skill aims for 150-220 lines for a typical PR body. 300+ lines is a smell, not a virtue. If your draft exceeds 250 lines, run a tightening pass: every sentence that does not change the reviewer's understanding must be cut.

Read the full file on GitHub · 341 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 341 lines · 131 tokens per session scan A d07254e9d0b9

Subscribe to this mod's changes

pr-description-skill is a skill published in the GitHub repository microsoft/apm (3,687 stars, last pushed today), licensed MIT. It adds 131 tokens to every session and 4,074 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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