What a Backtick Bash Line in SKILL.md Actually Does

The correct answer is "Claude Code runs the command first and substitutes its output."

This is dynamic context injection: Claude Code runs git diff HEAD before Claude ever sees the skill content, and substitutes the command's output in the line's place. The skill arrives with live data already inlined, not a description of how to go get that data — a meaningful difference from a static instruction file. A fenced ```! block does the same for multi-line commands.

The distractors describe the wrong mechanism: Claude doesn't decide whether to run it as an ordinary tool call the way a plain instruction would prompt it to (the substitution happens automatically, before Claude reads anything); the line isn't rendered as literal text for a human to run by hand; and it isn't skipped unless the skill sets allowed-tools — dynamic context injection runs regardless of that field.